This definition of SCHED_WARN_ON():
#define SCHED_WARN_ON(x) ((void)(x))
is not fully compatible with the 'real' WARN_ON_ONCE() primitive, as it
has no return value, so it cannot be used in conditionals.
Fix it.
Cc: Daniel Axtens <dja@axtens.net>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So I've noticed a number of instances where it was not obvious from the
code whether ->task_list was for a wait-queue head or a wait-queue entry.
Furthermore, there's a number of wait-queue users where the lists are
not for 'tasks' but other entities (poll tables, etc.), in which case
the 'task_list' name is actively confusing.
To clear this all up, name the wait-queue head and entry list structure
fields unambiguously:
struct wait_queue_head::task_list => ::head
struct wait_queue_entry::task_list => ::entry
For example, this code:
rqw->wait.task_list.next != &wait->task_list
... is was pretty unclear (to me) what it's doing, while now it's written this way:
rqw->wait.head.next != &wait->entry
... which makes it pretty clear that we are iterating a list until we see the head.
Other examples are:
list_for_each_entry_safe(pos, next, &x->task_list, task_list) {
list_for_each_entry(wq, &fence->wait.task_list, task_list) {
... where it's unclear (to me) what we are iterating, and during review it's
hard to tell whether it's trying to walk a wait-queue entry (which would be
a bug), while now it's written as:
list_for_each_entry_safe(pos, next, &x->head, entry) {
list_for_each_entry(wq, &fence->wait.head, entry) {
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The key hashed waitqueue data structures and their initialization
was done in the main scheduler file for no good reason, move them
to sched/wait_bit.c instead.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The wait_bit*() types and APIs are mixed into wait.h, but they
are a pretty orthogonal extension of wait-queues.
Furthermore, only about 50 kernel files use these APIs, while
over 1000 use the regular wait-queue functionality.
So clean up the main wait.h by moving the wait-bit functionality
out of it, into a separate .h and .c file:
include/linux/wait_bit.h for types and APIs
kernel/sched/wait_bit.c for the implementation
Update all header dependencies.
This reduces the size of wait.h rather significantly, by about 30%.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So wait-bit-queue head variables are often named:
struct wait_bit_queue *q
... which is a bit ambiguous and super confusing, because
they clearly suggest wait-queue head semantics and behavior
(they rhyme with the old wait_queue_t *q naming), while they
are extended wait-queue _entries_, not heads!
They are misnomers in two ways:
- the 'wait_bit_queue' leaves open the question of whether
it's an entry or a head
- the 'q' parameter and local variable naming falsely implies
that it's a 'queue' - while it's an entry.
This resulted in sometimes confusing cases such as:
finish_wait(wq, &q->wait);
where the 'q' is not a wait-queue head, but a wait-bit-queue entry.
So improve this all by standardizing wait-bit-queue nomenclature
similar to wait-queue head naming:
struct wait_bit_queue => struct wait_bit_queue_entry
q => wbq_entry
Which makes it all a much clearer:
struct wait_bit_queue_entry *wbq_entry
... and turns the former confusing piece of code into:
finish_wait(wq_head, &wbq_entry->wq_entry;
which IMHO makes it apparently clear what we are doing,
without having to analyze the context of the code: we are
adding a wait-queue entry to a regular wait-queue head,
which entry is embedded in a wait-bit-queue entry.
I'm not a big fan of acronyms, but repeating wait_bit_queue_entry
in field and local variable names is too long, so Hopefully it's
clear enough that 'wq_' prefixes stand for wait-queues, while
'wbq_' prefixes stand for wait-bit-queues.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename 'struct wait_bit_queue::wait' to ::wq_entry, to more clearly
name it as a wait-queue entry.
Propagate it to a couple of usage sites where the wait-bit-queue internals
are exposed.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The wait-queue head parameters and variables are named in a
couple of ways, we have the following variants currently:
wait_queue_head_t *q
wait_queue_head_t *wq
wait_queue_head_t *head
In particular the 'wq' naming is ambiguous in the sense whether it's
a wait-queue head or entry name - as entries were often named 'wait'.
( Not to mention the confusion of any readers coming over from
workqueue-land. )
Standardize all this around a single, unambiguous parameter and
variable name:
struct wait_queue_head *wq_head
which is easy to grep for and also rhymes nicely with the wait-queue
entry naming:
struct wait_queue_entry *wq_entry
Also rename:
struct __wait_queue_head => struct wait_queue_head
... and use this struct type to migrate from typedefs usage to 'struct'
usage, which is more in line with existing kernel practices.
Don't touch any external users and preserve the main wait_queue_head_t
typedef.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the various wait-queue entry variables in include/linux/wait.h
and kernel/sched/wait.c are named in a colorfully inconsistent
way:
wait_queue_entry_t *wait
wait_queue_entry_t *__wait (even in plain C code!)
wait_queue_entry_t *q (!)
wait_queue_entry_t *new (making anyone who knows C++ cringe)
wait_queue_entry_t *old
I think part of the reason for the inconsistency is the constant
apparent confusion about what a wait queue 'head' versus 'entry' is.
( Some of the documentation talks about a 'wait descriptor', which is
the wait-queue entry itself - further adding to the confusion. )
The most common name is 'wait', but that in itself is somewhat
ambiguous as well, as it does not really make it clear whether
it's a wait-queue entry or head.
To improve all this name the wait-queue entry structure parameters
and variables consistently and push through this naming into all
the wait.h and wait.c code:
struct wait_queue_entry *wq_entry
The 'wq_' prefix makes it easy to grep for, and we also use the
opportunity to move away from the typedef to a plain 'struct' naming:
in the kernel we typically reserve typedefs for cases where a
C structure is really small and somewhat opaque - such as pte_t.
wait-queue entries are neither small nor opaque, so use the more
standard 'struct xxx_entry' list management code nomenclature instead.
( We don't touch external users, and we preserve the typedef as well
for actual wait-queue users, to reduce unnecessary churn. )
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename:
wait_queue_t => wait_queue_entry_t
'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.
Start sorting this out by renaming it to 'wait_queue_entry_t'.
This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Thomas Gleixner:
"Two small fixes for the schedulre core:
- Use the proper switch_mm() variant in idle_task_exit() because that
code is not called with interrupts disabled.
- Fix a confusing typo in a printk"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off()
sched/fair: Fix typo in printk message
Revert commit 39b64aa1c0 (cpufreq: schedutil: Reduce frequencies
slower) that introduced unintentional changes in behavior leading
to adverse effects on some systems.
Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
idle_task_exit() can be called with IRQs on x86 on and therefore
should use switch_mm(), not switch_mm_irqs_off().
This doesn't seem to cause any problems right now, but it will
confuse my upcoming TLB flush changes. Nonetheless, I think it
should be backported because it's trivial. There won't be any
meaningful performance impact because idle_task_exit() is only
used when offlining a CPU.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: f98db6013c ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler")
Link: http://lkml.kernel.org/r/ca3d1a9fa93a0b49f5a8ff729eda3640fb6abdf9.1497034141.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
'schedstats' kernel parameter should be set to enable/disable, so
correct the printk hint saying that it should be set to 'enable'
rather than 'enabled' to enable scheduler tracepoints.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1496995229-31245-1-git-send-email-marcin.nowakowski@imgtec.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The synchronize_rcu_mult() function now detects duplicate requests
for the same grace-period flavor and waits only once for each flavor.
This commit therefore removes the ugly #ifdef from sched_cpu_deactivate()
because synchronize_rcu_mult(call_rcu, call_rcu_sched) now does what
the #ifdef used to be needed for.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Deferrable vmstat_updater was missing in commit:
c1de45ca83 ("sched/idle: Add support for tasks that inject idle")
Add it back.
Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1496803742-38274-1-git-send-email-aubrey.li@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The stop class is invoked through stop_machine only.
This is dead code on UP builds.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170529210302.26868-3-nicolas.pitre@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We have been facing some problems with self-suspending constrained
deadline tasks. The main reason is that the original CBS was not
designed for such sort of tasks.
One problem reported by Xunlei Pang takes place when a task
suspends, and then is awakened before the deadline, but so close
to the deadline that its remaining runtime can cause the task
to have an absolute density higher than allowed. In such situation,
the original CBS assumes that the task is facing an early activation,
and so it replenishes the task and set another deadline, one deadline
in the future. This rule works fine for implicit deadline tasks.
Moreover, it allows the system to adapt the period of a task in which
the external event source suffered from a clock drift.
However, this opens the window for bandwidth leakage for constrained
deadline tasks. For instance, a task with the following parameters:
runtime = 5 ms
deadline = 7 ms
[density] = 5 / 7 = 0.71
period = 1000 ms
If the task runs for 1 ms, and then suspends for another 1ms,
it will be awakened with the following parameters:
remaining runtime = 4
laxity = 5
presenting a absolute density of 4 / 5 = 0.80.
In this case, the original CBS would assume the task had an early
wakeup. Then, CBS will reset the runtime, and the absolute deadline will
be postponed by one relative deadline, allowing the task to run.
The problem is that, if the task runs this pattern forever, it will keep
receiving bandwidth, being able to run 1ms every 2ms. Following this
behavior, the task would be able to run 500 ms in 1 sec. Thus running
more than the 5 ms / 1 sec the admission control allowed it to run.
Trying to address the self-suspending case, Luca Abeni, Giuseppe
Lipari, and Juri Lelli [1] revisited the CBS in order to deal with
self-suspending tasks. In the new approach, rather than
replenishing/postponing the absolute deadline, the revised wakeup rule
adjusts the remaining runtime, reducing it to fit into the allowed
density.
A revised version of the idea is:
At a given time t, the maximum absolute density of a task cannot be
higher than its relative density, that is:
runtime / (deadline - t) <= dl_runtime / dl_deadline
Knowing the laxity of a task (deadline - t), it is possible to move
it to the other side of the equality, thus enabling to define max
remaining runtime a task can use within the absolute deadline, without
over-running the allowed density:
runtime = (dl_runtime / dl_deadline) * (deadline - t)
For instance, in our previous example, the task could still run:
runtime = ( 5 / 7 ) * 5
runtime = 3.57 ms
Without causing damage for other deadline tasks. It is note worthy
that the laxity cannot be negative because that would cause a negative
runtime. Thus, this patch depends on the patch:
df8eac8caf ("sched/deadline: Throttle a constrained deadline task activated after the deadline")
Which throttles a constrained deadline task activated after the
deadline.
Finally, it is also possible to use the revised wakeup rule for
all other tasks, but that would require some more discussions
about pros and cons.
Reported-by: Xunlei Pang <xpang@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
[peterz: replaced dl_is_constrained with dl_is_implicit]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/5c800ab3a74a168a84ee5f3f84d12a02e11383be.1495803804.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a contrained task is throttled by dl_check_constrained_dl(),
it may carry the remaining positive runtime, as a result when
dl_task_timer() fires and calls replenish_dl_entity(), it will
not be replenished correctly due to the positive dl_se->runtime.
This patch assigns its runtime to 0 if positive after throttling.
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: df8eac8caf ("sched/deadline: Throttle a constrained deadline task activated after the deadline)
Link: http://lkml.kernel.org/r/1494421417-27550-1-git-send-email-xlpang@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit introduces a per-runqueue "extra utilization" that can be
reclaimed by deadline tasks. In this way, the maximum fraction of CPU
time that can reclaimed by deadline tasks is fixed (and configurable)
and does not depend on the total deadline utilization.
The GRUB accounting rule is modified to add this "extra utilization"
to the inactive utilization of the runqueue, and to avoid reclaiming
more than a maximum fraction of the CPU time.
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-10-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of decreasing the runtime as "dq = -Uact dt" (eventually
divided by the maximum utilization available for deadline tasks),
decrease it as "dq = -max{u, (1 - Uinact)} dt", where u is the task
utilization and Uinact is the "inactive utilization".
In this way, the maximum fraction of CPU time that can be reclaimed
is given by the total utilization of deadline tasks.
This approach solves a fairness issue with "traditional" global GRUB
reclaiming: using the traditional GRUB algorithm, if tasks are
allocated to the various cores in a non-uniform way, the
reclaiming mechanism allows some tasks to reclaim more time than
others. This issue is visible starting 11 time-consuming tasks with
runtime 10ms and period 30ms (total utilization 3.666) on a 4-cores
system: some tasks will receive much more than the reserved runtime
(thanks to the reclaiming mechanism), while other tasks will receive
less than the reserved runtime.
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-9-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The total rq utilization is defined as the sum of the utilisations of
tasks that are "assigned" to a runqueue, independently from their state
(TASK_RUNNING or blocked)
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-8-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch introduces the SCHED_FLAG_RECLAIM flag to specify
that a DL task is allowed to reclaim unused CPU time (using
the GRUB algorithm).
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-7-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Original GRUB tends to reclaim 100% of the CPU time... And this
allows a CPU hog to starve non-deadline tasks.
To address this issue, allow the scheduler to reclaim only a
specified fraction of CPU time, stored in the new "bw_ratio"
field of the dl runqueue structure.
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-6-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
According to the GRUB (Greedy Reclaimation of Unused Bandwidth)
reclaiming algorithm, the runtime is not decreased as "dq = -dt",
but as "dq = -Uact dt" (where Uact is the per-runqueue active
utilization).
Hence, this commit modifies the runtime accounting rule in
update_curr_dl() to implement the GRUB rule.
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-5-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that the inactive timer can be armed to fire at the 0-lag time,
it is possible to use inactive_task_timer() to update the total
-deadline utilization (dl_b->total_bw) at the correct time, fixing
dl_overflow() and __setparam_dl().
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-4-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch implements a more theoretically sound algorithm for
tracking active utilization: instead of decreasing it when a
task blocks, use a timer (the "inactive timer", named after the
"Inactive" task state of the GRUB algorithm) to decrease the
active utilization at the so called "0-lag time".
Tested-by: Claudio Scordino <claudio@evidence.eu.com>
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-3-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Active utilization is defined as the total utilization of active
(TASK_RUNNING) tasks queued on a runqueue. Hence, it is increased
when a task wakes up and is decreased when a task blocks.
When a task is migrated from CPUi to CPUj, immediately subtract the
task's utilization from CPUi and add it to CPUj. This mechanism is
implemented by modifying the pull and push functions.
Note: this is not fully correct from the theoretical point of view
(the utilization should be removed from CPUi only at the 0 lag
time), a more theoretically sound solution is presented in the
next patches.
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Luca Abeni <luca.abeni@unitn.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@arm.com>
Cc: Claudio Scordino <claudio@evidence.eu.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/1495138417-6203-2-git-send-email-luca.abeni@santannapisa.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Hackbench recently suffered a bunch of pain, first by commit:
4c77b18cf8 ("sched/fair: Make select_idle_cpu() more aggressive")
and then by commit:
c743f0a5c5 ("sched/fair, cpumask: Export for_each_cpu_wrap()")
which fixed a bug in the initial for_each_cpu_wrap() implementation
that made select_idle_cpu() even more expensive. The bug was that it
would skip over CPUs when bits were consequtive in the bitmask.
This however gave me an idea to fix select_idle_cpu(); where the old
scheme was a cliff-edge throttle on idle scanning, this introduces a
more gradual approach. Instead of stopping to scan entirely, we limit
how many CPUs we scan.
Initial benchmarks show that it mostly recovers hackbench while not
hurting anything else, except Mason's schbench, but not as bad as the
old thing.
It also appears to recover the tbench high-end, which also suffered like
hackbench.
Tested-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hpa@zytor.com
Cc: kitsunyan <kitsunyan@inbox.ru>
Cc: linux-kernel@vger.kernel.org
Cc: lvenanci@redhat.com
Cc: riel@redhat.com
Cc: xiaolong.ye@intel.com
Link: http://lkml.kernel.org/r/20170517105350.hk5m4h4jb6dfr65a@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The more strict early boot preemption warnings found that
__set_sched_clock_stable() was incorrectly assuming we'd still be
running on a single CPU:
BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
caller is debug_smp_processor_id+0x1c/0x1e
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2-00108-g1c3c5ea #1
Call Trace:
dump_stack+0x110/0x192
check_preemption_disabled+0x10c/0x128
? set_debug_rodata+0x25/0x25
debug_smp_processor_id+0x1c/0x1e
sched_clock_init_late+0x27/0x87
[...]
Fix it by disabling IRQs.
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: lkp@01.org
Cc: tipbuild@zytor.com
Link: http://lkml.kernel.org/r/20170524065202.v25vyu7pvba5mhpd@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
might_sleep() and smp_processor_id() checks are enabled after the boot
process is done. That hides bugs in the SMP bringup and driver
initialization code.
Enable it right when the scheduler starts working, i.e. when init task and
kthreadd have been created and right before the idle task enables
preemption.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170516184736.272225698@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A customer has reported a soft-lockup when running an intensive
memory stress test, where the trace on multiple CPU's looks like this:
RIP: 0010:[<ffffffff810c53fe>]
[<ffffffff810c53fe>] native_queued_spin_lock_slowpath+0x10e/0x190
...
Call Trace:
[<ffffffff81182d07>] queued_spin_lock_slowpath+0x7/0xa
[<ffffffff811bc331>] change_protection_range+0x3b1/0x930
[<ffffffff811d4be8>] change_prot_numa+0x18/0x30
[<ffffffff810adefe>] task_numa_work+0x1fe/0x310
[<ffffffff81098322>] task_work_run+0x72/0x90
Further investigation showed that the lock contention here is pmd_lock().
The task_numa_work() function makes sure that only one thread is let to perform
the work in a single scan period (via cmpxchg), but if there's a thread with
mmap_sem locked for writing for several periods, multiple threads in
task_numa_work() can build up a convoy waiting for mmap_sem for read and then
all get unblocked at once.
This patch changes the down_read() to the trylock version, which prevents the
build up. For a workload experiencing mmap_sem contention, it's probably better
to postpone the NUMA balancing work anyway. This seems to have fixed the soft
lockups involving pmd_lock(), which is in line with the convoy theory.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170515131316.21909-1-vbabka@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With CONFIG_RT_GROUP_SCHED=y, do_sched_rt_period_timer() sequentially
takes each CPU's rq->lock. On a large, busy system, the cumulative time it
takes to acquire each lock can be excessive, even triggering a watchdog
timeout.
If rt_rq->rt_time and rt_rq->rt_nr_running are both zero, this function does
nothing while holding the lock, so don't bother taking it at all.
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a767637b-df85-912f-ba69-c90ee00a3fb6@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When priority inheritance was added back in 2.6.18 to sched_setscheduler(), it
added a path to taking an rt-mutex wait_lock, which is not IRQ safe. As PI
is not a common occurrence, lockdep will likely never trigger if
sched_setscheduler was called from interrupt context. A BUG_ON() was added
to trigger if __sched_setscheduler() was ever called from interrupt context
because there was a possibility to take the wait_lock.
Today the wait_lock is irq safe, but the path to taking it in
sched_setscheduler() is the same as the path to taking it from normal
context. The wait_lock is taken with raw_spin_lock_irq() and released with
raw_spin_unlock_irq() which will indiscriminately enable interrupts,
which would be bad in interrupt context.
The problem is that normalize_rt_tasks, which is called by triggering the
sysrq nice-all-RT-tasks was changed to call __sched_setscheduler(), and this
is done from interrupt context!
Now __sched_setscheduler() takes a "pi" parameter that is used to know if
the priority inheritance should be called or not. As the BUG_ON() only cares
about calling the PI code, it should only bug if called from interrupt
context with the "pi" parameter set to true.
Reported-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Tested-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: dbc7f069b9 ("sched: Use replace normalize_task() with __sched_setscheduler()")
Link: http://lkml.kernel.org/r/20170308124654.10e598f2@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
pick_next_pushable_dl_task(rq) has BUG_ON(rq->cpu != task_cpu(task))
when it returns a task other than NULL, which means that task_cpu(task)
must be rq->cpu. So if task == next_task, then task_cpu(next_task) must
be rq->cpu as well. Remove the redundant condition and make the code simpler.
This way one unnecessary branch and two LOAD operations can be avoided.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: <kernel-team@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1494551159-22367-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
pick_next_pushable_task(rq) has BUG_ON(rq_cpu != task_cpu(task)) when
it returns a task other than NULL, which means that task_cpu(task) must
be rq->cpu. So if task == next_task, then task_cpu(next_task) must be
rq->cpu as well. Remove the redundant condition and make the code simpler.
This way one unnecessary branch and two LOAD operations can be avoided.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: <kernel-team@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1494551143-22219-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that we've added llist_for_each_entry_safe(), use it to simplify
an open coded version of it in sched_ttwu_pending().
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <kernel-team@lge.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1494549584-11730-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
* intel_pstate:
cpufreq: intel_pstate: Document the current behavior and user interface
* pm-cpufreq:
cpufreq: dbx500: add a Kconfig symbol
* pm-cpufreq-sched:
cpufreq: schedutil: use now as reference when aggregating shared policy requests
Currently, rq->leaf_cfs_rq_list is a traversal ordered list of all
live cfs_rqs which have ever been active on the CPU; unfortunately,
this makes update_blocked_averages() O(# total cgroups) which isn't
scalable at all.
This shows up as a small CPU consumption and scheduling latency
increase in the load balancing path in systems with CPU controller
enabled across most cgroups. In an edge case where temporary cgroups
were leaking, this caused the kernel to consume good several tens of
percents of CPU cycles running update_blocked_averages(), each run
taking multiple millisecs.
This patch fixes the issue by taking empty and fully decayed cfs_rqs
off the rq->leaf_cfs_rq_list.
Signed-off-by: Tejun Heo <tj@kernel.org>
[ Added cfs_rq_is_decayed() ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Chris Mason <clm@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170426004350.GB3222@wtj.duckdns.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to allow leaf_cfs_rq_list to remove entries switch the
bandwidth hotplug code over to the task_groups list.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170504133122.a6qjlj3hlblbjxux@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There's a discrepancy in naming between the sched_domain and
sched_group cpumask accessor. Since we're doing changes, fix it.
$ git grep sched_group_cpus | wc -l
28
$ git grep sched_domain_span | wc -l
38
Suggests changing sched_group_cpus() into sched_group_span():
for i in `git grep -l sched_group_cpus`
do
sed -ie 's/sched_group_cpus/sched_group_span/g' $i
done
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since sched_group_mask() is now an independent cpumask (it no longer
masks sched_group_cpus()), rename the thing.
Suggested-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While writing the comments, it occurred to me that:
sg_cpus & sg_mask == sg_mask
at least conceptually; the !overlap case sets the all 1s mask. If we
correct that we can simplify things and directly use sg_mask.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We want to attain:
sg_cpus() & sg_mask() == sg_mask()
for this to be so we must initialize sg_mask() to sg_cpus() for the
!overlap case (its currently cpumask_setall()).
Since the code makes my head hurt bad, rewrite it into a simpler form,
inspired by the now fixed overlap code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Try and describe what this code is about..
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When building the overlapping groups we need to attach a consistent
sched_group_capacity structure. That is, all 'identical' sched_group's
should have the _same_ sched_group_capacity.
This can (once again) be demonstrated with a topology like:
node 0 1 2 3
0: 10 20 30 20
1: 20 10 20 30
2: 30 20 10 20
3: 20 30 20 10
But we need at least 2 CPUs per node for this to show up, after all,
if there is only one CPU per node, our CPU @i is per definition a
unique CPU that reaches this domain (aka balance-cpu).
Given the above NUMA topo and 2 CPUs per node:
[] CPU0 attaching sched-domain(s):
[] domain-0: span=0,4 level=DIE
[] groups: 0:{ span=0 }, 4:{ span=4 }
[] domain-1: span=0-1,3-5,7 level=NUMA
[] groups: 0:{ span=0,4 mask=0,4 cap=2048 }, 1:{ span=1,5 mask=1,5 cap=2048 }, 3:{ span=3,7 mask=3,7 cap=2048 }
[] domain-2: span=0-7 level=NUMA
[] groups: 0:{ span=0-1,3-5,7 mask=0,4 cap=6144 }, 2:{ span=1-3,5-7 mask=2,6 cap=6144 }
[] CPU1 attaching sched-domain(s):
[] domain-0: span=1,5 level=DIE
[] groups: 1:{ span=1 }, 5:{ span=5 }
[] domain-1: span=0-2,4-6 level=NUMA
[] groups: 1:{ span=1,5 mask=1,5 cap=2048 }, 2:{ span=2,6 mask=2,6 cap=2048 }, 4:{ span=0,4 mask=0,4 cap=2048 }
[] domain-2: span=0-7 level=NUMA
[] groups: 1:{ span=0-2,4-6 mask=1,5 cap=6144 }, 3:{ span=0,2-4,6-7 mask=3,7 cap=6144 }
Observe how CPU0-domain1-group0 and CPU1-domain1-group4 are the
'same' but have a different id (0 vs 4).
To fix this, use the group balance CPU to select the SGC. This means
we have to compute the full mask for each CPU and require a second
temporary mask to store the group mask in (it otherwise lives in the
SGC).
The fixed topology looks like:
[] CPU0 attaching sched-domain(s):
[] domain-0: span=0,4 level=DIE
[] groups: 0:{ span=0 }, 4:{ span=4 }
[] domain-1: span=0-1,3-5,7 level=NUMA
[] groups: 0:{ span=0,4 mask=0,4 cap=2048 }, 1:{ span=1,5 mask=1,5 cap=2048 }, 3:{ span=3,7 mask=3,7 cap=2048 }
[] domain-2: span=0-7 level=NUMA
[] groups: 0:{ span=0-1,3-5,7 mask=0,4 cap=6144 }, 2:{ span=1-3,5-7 mask=2,6 cap=6144 }
[] CPU1 attaching sched-domain(s):
[] domain-0: span=1,5 level=DIE
[] groups: 1:{ span=1 }, 5:{ span=5 }
[] domain-1: span=0-2,4-6 level=NUMA
[] groups: 1:{ span=1,5 mask=1,5 cap=2048 }, 2:{ span=2,6 mask=2,6 cap=2048 }, 0:{ span=0,4 mask=0,4 cap=2048 }
[] domain-2: span=0-7 level=NUMA
[] groups: 1:{ span=0-2,4-6 mask=1,5 cap=6144 }, 3:{ span=0,2-4,6-7 mask=3,7 cap=6144 }
Debugged-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: e3589f6c81 ("sched: Allow for overlapping sched_domain spans")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add sgc::id to easier spot domain construction issues.
Take the opportunity to slightly rework the group printing, because
adding more "(id: %d)" strings makes the entire thing very hard to
read. Also the individual groups are very hard to separate, so add
explicit visual grouping, which allows replacing all the "(%s: %d)"
format things with shorter "%s=%d" variants.
Then fix up some inconsistencies in surrounding prints for domains.
The end result looks like:
[] CPU0 attaching sched-domain(s):
[] domain-0: span=0,4 level=DIE
[] groups: 0:{ span=0 }, 4:{ span=4 }
[] domain-1: span=0-1,3-5,7 level=NUMA
[] groups: 0:{ span=0,4 mask=0,4 cap=2048 }, 1:{ span=1,5 mask=1,5 cap=2048 }, 3:{ span=3,7 mask=3,7 cap=2048 }
[] domain-2: span=0-7 level=NUMA
[] groups: 0:{ span=0-1,3-5,7 mask=0,4 cap=6144 }, 2:{ span=1-3,5-7 mask=2,6 cap=6144 }
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move the allocation of topology specific cpumasks into the topology
code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The point of sched_group_mask is to select those CPUs from
sched_group_cpus that can actually arrive at this balance domain.
The current code gets it wrong, as can be readily demonstrated with a
topology like:
node 0 1 2 3
0: 10 20 30 20
1: 20 10 20 30
2: 30 20 10 20
3: 20 30 20 10
Where (for example) domain 1 on CPU1 ends up with a mask that includes
CPU0:
[] CPU1 attaching sched-domain:
[] domain 0: span 0-2 level NUMA
[] groups: 1 (mask: 1), 2, 0
[] domain 1: span 0-3 level NUMA
[] groups: 0-2 (mask: 0-2) (cpu_capacity: 3072), 0,2-3 (cpu_capacity: 3072)
This causes sched_balance_cpu() to compute the wrong CPU and
consequently should_we_balance() will terminate early resulting in
missed load-balance opportunities.
The fixed topology looks like:
[] CPU1 attaching sched-domain:
[] domain 0: span 0-2 level NUMA
[] groups: 1 (mask: 1), 2, 0
[] domain 1: span 0-3 level NUMA
[] groups: 0-2 (mask: 1) (cpu_capacity: 3072), 0,2-3 (cpu_capacity: 3072)
(note: this relies on OVERLAP domains to always have children, this is
true because the regular topology domains are still here -- this is
before degenerate trimming)
Debugged-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: e3589f6c81 ("sched: Allow for overlapping sched_domain spans")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Its an obsolete debug mechanism and future code wants to rely on
properties this undermines.
Namely, it would be good to assume that SD_OVERLAP domains have
children, but if we build the entire hierarchy with SD_OVERLAP this is
obviously false.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The group mask is always used in intersection with the group CPUs. So,
when building the group mask, we don't have to care about CPUs that are
not part of the group.
Signed-off-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lwang@redhat.com
Cc: riel@redhat.com
Link: http://lkml.kernel.org/r/1492717903-5195-2-git-send-email-lvenanci@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We want sched_groups to be sibling child domains (or individual CPUs
when there are no child domains). Furthermore, since the first group
of a domain should include the CPU of that domain, the first group of
each domain should match the child domain.
Verify this is indeed so.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to determine the balance_cpu (for should_we_balance()) we need
the sched_group_mask() for overlapping domains.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that the first group will always be the previous domain of this
@cpu this can be simplified.
In fact, writing the code now removed should've been a big clue I was
doing it wrong :/
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When building the overlapping groups, we very obviously should start
with the previous domain of _this_ @cpu, not CPU-0.
This can be readily demonstrated with a topology like:
node 0 1 2 3
0: 10 20 30 20
1: 20 10 20 30
2: 30 20 10 20
3: 20 30 20 10
Where (for example) CPU1 ends up generating the following nonsensical groups:
[] CPU1 attaching sched-domain:
[] domain 0: span 0-2 level NUMA
[] groups: 1 2 0
[] domain 1: span 0-3 level NUMA
[] groups: 1-3 (cpu_capacity = 3072) 0-1,3 (cpu_capacity = 3072)
Where the fact that domain 1 doesn't include a group with span 0-2 is
the obvious fail.
With patch this looks like:
[] CPU1 attaching sched-domain:
[] domain 0: span 0-2 level NUMA
[] groups: 1 0 2
[] domain 1: span 0-3 level NUMA
[] groups: 0-2 (cpu_capacity = 3072) 0,2-3 (cpu_capacity = 3072)
Debugged-by: Lauro Ramos Venancio <lvenanci@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: e3589f6c81 ("sched: Allow for overlapping sched_domain spans")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
More users for for_each_cpu_wrap() have appeared. Promote the construct
to generic cpumask interface.
The implementation is slightly modified to reduce arguments.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Lauro Ramos Venancio <lvenanci@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: lwang@redhat.com
Link: http://lkml.kernel.org/r/20170414122005.o35me2h5nowqkxbv@hirez.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
With our switch to stable delayed until late_initcall(), the most
likely cause of hitting mark_tsc_unstable() is the watchdog. The
watchdog typically only triggers when creative BIOS'es fiddle with the
TSC to hide SMI latency.
Since the watchdog can only detect TSC fiddling after the fact all TSC
clocks (including userspace GTOD) can already have reported funny
values.
The only way to fully avoid this, is manually marking the TSC unstable
at boot. Suggest people do this on their broken systems.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Core2 marks its TSC unstable in ACPI Processor Idle, which is probed
after sched_init_smp(). Luckily it appears both acpi_processor and
intel_idle (which has a similar check) are mandatory built-in.
This means we can delay switching to stable until after these drivers
have ran (if they were modules, this would be impossible).
Delay the stable switch to late_initcall() to allow these drivers to
mark TSC unstable and avoid difficult stable->unstable transitions.
Reported-by: Lofstedt, Marta <marta.lofstedt@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ville reported that on his Core2, which has TSC stop in idle, we would
always report very short idle durations. He tracked this down to
commit:
e93e59ce5b ("cpuidle: Replace ktime_get() with local_clock()")
which replaces ktime_get() with local_clock().
Add a sched_clock_idle_wakeup_event() call, which will re-sync the
clock with ktime_get_ns() when TSC is unstable and no-op otherwise.
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: e93e59ce5b ("cpuidle: Replace ktime_get() with local_clock()")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit:
2bacec8c31 ("sched: touch softlockup watchdog after idling")
introduced the touch_softlockup_watchdog_sched() call without
justification and I feel sched_clock management is not the right
place, it should only be concerned with producing semi coherent time.
If this causes watchdog thingies, we can find a better place.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The argument to sched_clock_idle_wakeup_event() has not been used in a
long time. Remove it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently we keep sched_clock_tick() active for stable TSC in order to
keep the per-CPU state semi up-to-date. The (obvious) problem is that
by the time we detect TSC is borked, our per-CPU state is also borked.
So hook into the clocksource watchdog and call a method after we've
found it to still be stable.
There's the obvious race where the TSC goes wonky between finding it
stable and us running the callback, but closing that is too much work
and not really worth it, since we're already detecting TSC wobbles
after the fact, so we cannot, per definition, fully avoid funny clock
values.
And since the watchdog runs less often than the tick, this is also an
optimization.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for not keeping the sched_clock_tick() active for
stable TSC, we need to explicitly initialize all per-CPU state
before switching back to unstable.
Note: this patch looses the __gtod_offset calculation; it will be
restored in the next one.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the current implementation of load/util_avg, we assume that the
ongoing time segment has fully elapsed, and util/load_sum is divided
by LOAD_AVG_MAX, even if part of the time segment still remains to
run. As a consequence, this remaining part is considered as idle time
and generates unexpected variations of util_avg of a busy CPU in the
range [1002..1024[ whereas util_avg should stay at 1023.
In order to keep the metric stable, we should not consider the ongoing
time segment when computing load/util_avg but only the segments that
have already fully elapsed. But to not consider the current time
segment adds unwanted latency in the load/util_avg responsivness
especially when the time is scaled instead of the contribution.
Instead of waiting for the current time segment to have fully elapsed
before accounting it in load/util_avg, we can already account the
elapsed part but change the range used to compute load/util_avg
accordingly.
At the very beginning of a new time segment, the past segments have
been decayed and the max value is LOAD_AVG_MAX*y. At the very end of
the current time segment, the max value becomes:
LOAD_AVG_MAX*y + 1024(us) (== LOAD_AVG_MAX)
In fact, the max value is:
LOAD_AVG_MAX*y + sa->period_contrib
at any time in the time segment.
Taking advantage of the fact that:
LOAD_AVG_MAX*y == LOAD_AVG_MAX-1024
the range becomes [0..LOAD_AVG_MAX-1024+sa->period_contrib].
As the elapsed part is already accounted in load/util_sum, we update
the max value according to the current position in the time segment
instead of removing its contribution.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1493188076-2767-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
I finally got around to creating trampolines for dynamically allocated
ftrace_ops with using synchronize_rcu_tasks(). For users of the ftrace
function hook callbacks, like perf, that allocate the ftrace_ops
descriptor via kmalloc() and friends, ftrace was not able to optimize
the functions being traced to use a trampoline because they would also
need to be allocated dynamically. The problem is that they cannot be
freed when CONFIG_PREEMPT is set, as there's no way to tell if a task
was preempted on the trampoline. That was before Paul McKenney
implemented synchronize_rcu_tasks() that would make sure all tasks
(except idle) have scheduled out or have entered user space.
While testing this, I triggered this bug:
BUG: unable to handle kernel paging request at ffffffffa0230077
...
RIP: 0010:0xffffffffa0230077
...
Call Trace:
schedule+0x5/0xe0
schedule_preempt_disabled+0x18/0x30
do_idle+0x172/0x220
What happened was that the idle task was preempted on the trampoline.
As synchronize_rcu_tasks() ignores the idle thread, there's nothing
that lets ftrace know that the idle task was preempted on a trampoline.
The idle task shouldn't need to ever enable preemption. The idle task
is simply a loop that calls schedule or places the cpu into idle mode.
In fact, having preemption enabled is inefficient, because it can
happen when idle is just about to call schedule anyway, which would
cause schedule to be called twice. Once for when the interrupt came in
and was returning back to normal context, and then again in the normal
path that the idle loop is running in, which would be pointless, as it
had already scheduled.
The only reason schedule_preempt_disable() enables preemption is to be
able to call sched_submit_work(), which requires preemption enabled. As
this is a nop when the task is in the RUNNING state, and idle is always
in the running state, there's no reason that idle needs to enable
preemption. But that means it cannot use schedule_preempt_disable() as
other callers of that function require calling sched_submit_work().
Adding a new function local to kernel/sched/ that allows idle to call
the scheduler without enabling preemption, fixes the
synchronize_rcu_tasks() issue, as well as removes the pointless spurious
schedule calls caused by interrupts happening in the brief window where
preemption is enabled just before it calls schedule.
Reviewed: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170414084809.3dacde2a@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull RCU updates from Ingo Molnar:
"The main changes are:
- Debloat RCU headers
- Parallelize SRCU callback handling (plus overlapping patches)
- Improve the performance of Tree SRCU on a CPU-hotplug stress test
- Documentation updates
- Miscellaneous fixes"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (74 commits)
rcu: Open-code the rcu_cblist_n_lazy_cbs() function
rcu: Open-code the rcu_cblist_n_cbs() function
rcu: Open-code the rcu_cblist_empty() function
rcu: Separately compile large rcu_segcblist functions
srcu: Debloat the <linux/rcu_segcblist.h> header
srcu: Adjust default auto-expediting holdoff
srcu: Specify auto-expedite holdoff time
srcu: Expedite first synchronize_srcu() when idle
srcu: Expedited grace periods with reduced memory contention
srcu: Make rcutorture writer stalls print SRCU GP state
srcu: Exact tracking of srcu_data structures containing callbacks
srcu: Make SRCU be built by default
srcu: Fix Kconfig botch when SRCU not selected
rcu: Make non-preemptive schedule be Tasks RCU quiescent state
srcu: Expedite srcu_schedule_cbs_snp() callback invocation
srcu: Parallelize callback handling
kvm: Move srcu_struct fields to end of struct kvm
rcu: Fix typo in PER_RCU_NODE_PERIOD header comment
rcu: Use true/false in assignment to bool
rcu: Use bool value directly
...
Currently, sugov_next_freq_shared() uses last_freq_update_time as a
reference to decide when to start considering CPU contributions as
stale.
However, since last_freq_update_time is set by the last CPU that issued
a frequency transition, this might cause problems in certain cases. In
practice, the detection of stale utilization values fails whenever the
CPU with such values was the last to update the policy. For example (and
please note again that the SCHED_CPUFREQ_RT flag is not the problem
here, but only the detection of after how much time that flag has to be
considered stale), suppose a policy with 2 CPUs:
CPU0 | CPU1
|
| RT task scheduled
| SCHED_CPUFREQ_RT is set
| CPU1->last_update = now
| freq transition to max
| last_freq_update_time = now
|
more than TICK_NSEC nsecs
|
a small CFS wakes up |
CPU0->last_update = now1 |
delta_ns(CPU0) < TICK_NSEC* |
CPU0's util is considered |
delta_ns(CPU1) = |
last_freq_update_time - |
CPU1->last_update = 0 |
< TICK_NSEC |
CPU1 is still considered |
CPU1->SCHED_CPUFREQ_RT is set |
we stay at max (until CPU1 |
exits from idle) |
* delta_ns is actually negative as now1 > last_freq_update_time
While last_freq_update_time is a sensible reference for rate limiting,
it doesn't seem to be useful for working around stale CPU states.
Fix the problem by always considering now (time) as the reference for
deciding when CPUs have stale contributions.
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Pull livepatch updates from Jiri Kosina:
- a per-task consistency model is being added for architectures that
support reliable stack dumping (extending this, currently rather
trivial set, is currently in the works).
This extends the nature of the types of patches that can be applied
by live patching infrastructure. The code stems from the design
proposal made [1] back in November 2014. It's a hybrid of SUSE's
kGraft and RH's kpatch, combining advantages of both: it uses
kGraft's per-task consistency and syscall barrier switching combined
with kpatch's stack trace switching. There are also a number of
fallback options which make it quite flexible.
Most of the heavy lifting done by Josh Poimboeuf with help from
Miroslav Benes and Petr Mladek
[1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz
- module load time patch optimization from Zhou Chengming
- a few assorted small fixes
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
livepatch: add missing printk newlines
livepatch: Cancel transition a safe way for immediate patches
livepatch: Reduce the time of finding module symbols
livepatch: make klp_mutex proper part of API
livepatch: allow removal of a disabled patch
livepatch: add /proc/<pid>/patch_state
livepatch: change to a per-task consistency model
livepatch: store function sizes
livepatch: use kstrtobool() in enabled_store()
livepatch: move patching functions into patch.c
livepatch: remove unnecessary object loaded check
livepatch: separate enabled and patched states
livepatch/s390: add TIF_PATCH_PENDING thread flag
livepatch/s390: reorganize TIF thread flag bits
livepatch/powerpc: add TIF_PATCH_PENDING thread flag
livepatch/x86: add TIF_PATCH_PENDING thread flag
livepatch: create temporary klp_update_patch_state() stub
x86/entry: define _TIF_ALLWORK_MASK flags explicitly
stacktrace/x86: add function for detecting reliable stack traces
Pull locking updates from Ingo Molnar:
"The main changes in this cycle were:
- a big round of FUTEX_UNLOCK_PI improvements, fixes, cleanups and
general restructuring
- lockdep updates such as new checks for lock_downgrade()
- introduce the new atomic_try_cmpxchg() locking API and use it to
optimize refcount code generation
- ... plus misc fixes, updates and cleanups"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
MAINTAINERS: Add FUTEX SUBSYSTEM
futex: Clarify mark_wake_futex memory barrier usage
futex: Fix small (and harmless looking) inconsistencies
futex: Avoid freeing an active timer
rtmutex: Plug preempt count leak in rt_mutex_futex_unlock()
rtmutex: Fix more prio comparisons
rtmutex: Fix PI chain order integrity
sched,tracing: Update trace_sched_pi_setprio()
sched/rtmutex: Refactor rt_mutex_setprio()
rtmutex: Clean up
sched/deadline/rtmutex: Dont miss the dl_runtime/dl_period update
sched/rtmutex/deadline: Fix a PI crash for deadline tasks
rtmutex: Deboost before waking up the top waiter
locking/ww-mutex: Limit stress test to 2 seconds
locking/atomic: Fix atomic_try_cmpxchg() semantics
lockdep: Fix per-cpu static objects
futex: Drop hb->lock before enqueueing on the rtmutex
futex: Futex_unlock_pi() determinism
futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()
futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock()
...
- Rework the intel_pstate driver's sysfs interface to make it
more straightforward and more intuitive (Rafael Wysocki).
- Make intel_pstate support all processors which advertise HWP
(hardware-managed P-states) to the kernel in all operation modes
and make it use the load-based P-state selection algorithm on a
wider range of systems in the active mode (Rafael Wysocki).
- Add cpufreq driver for Tegra186 (Mikko Perttunen).
- Add support for Gemini Lake SoCs to intel_pstate (David Box).
- Add support for MT8176 and MT817x to the Mediatek cpufreq driver
and clean up that driver a bit (Daniel Kurtz).
- Clean up intel_pstate and optimize it slightly (Rafael Wysocki).
- Update the schedutil cpufreq governor, mostly to fix a couple of
issues with it related to specific workloads, and rework its sysfs
tunable and initialization a bit (Rafael Wysocki, Viresh Kumar).
- Fix minor issues in the imx6q, dbx500 and qoriq cpufreq drivers
(Christophe Jaillet, Irina Tirdea, Leonard Crestez, Viresh Kumar,
YuanTian Tang).
- Add file patterns for cpufreq DT bindings to MAINTAINERS (Geert
Uytterhoeven).
- Add support for "always on" power domains to the genpd (generic
power domains) framework and clean up that code somewhat (Ulf
Hansson, Lina Iyer, Viresh Kumar).
- Fix minor issues in the powernv cpuidle driver and clean it up
(Anton Blanchard, Gautham Shenoy).
- Move the AnalyzeSuspend utility under tools/power/pm-graph/ and
add an analogous boot-profiling utility called AnalyzeBoot to it
(Todd Brandt).
- Add rk3328 support to the rockchip-io AVS (Adaptive Voltage
Scaling) driver (David Wu).
- Fix minor issues in the cpuidle core, the intel_pstate_tracer
utility, the devfreq framework and the PM core documentation
(Chanwoo Choi, Doug Smythies, Johan Hovold, Marcin Nowakowski).
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Merge tag 'pm-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"This time the majority of changes go to the cpufreq subsystem (and to
the intel_pstate driver in particular) and there are some updates in
the generic power domains framework, cpuidle, tools and a couple of
other places.
One thing worth mentioning is that the intel_pstate's sysfs interface
has been reworked to be more consistent with the general expectations
of the cpufreq core and less confusing, hopefully for the better.
Also, we have a new cpufreq driver for Tegra186 and new hardware
support in intel_pstata and the Mediatek cpufreq driver.
Apart from that, the AnalyzeSuspend utility for system suspend
profiling gets a companion called AnalyzeBoot for the analogous
profiling of system boot and they both go into one place under
tools/power/pm-graph/.
The rest is mostly fixes, cleanups and code reorganization.
Specifics:
- Rework the intel_pstate driver's sysfs interface to make it more
straightforward and more intuitive (Rafael Wysocki).
- Make intel_pstate support all processors which advertise HWP
(hardware-managed P-states) to the kernel in all operation modes
and make it use the load-based P-state selection algorithm on a
wider range of systems in the active mode (Rafael Wysocki).
- Add cpufreq driver for Tegra186 (Mikko Perttunen).
- Add support for Gemini Lake SoCs to intel_pstate (David Box).
- Add support for MT8176 and MT817x to the Mediatek cpufreq driver
and clean up that driver a bit (Daniel Kurtz).
- Clean up intel_pstate and optimize it slightly (Rafael Wysocki).
- Update the schedutil cpufreq governor, mostly to fix a couple of
issues with it related to specific workloads, and rework its sysfs
tunable and initialization a bit (Rafael Wysocki, Viresh Kumar).
- Fix minor issues in the imx6q, dbx500 and qoriq cpufreq drivers
(Christophe Jaillet, Irina Tirdea, Leonard Crestez, Viresh Kumar,
YuanTian Tang).
- Add file patterns for cpufreq DT bindings to MAINTAINERS (Geert
Uytterhoeven).
- Add support for "always on" power domains to the genpd (generic
power domains) framework and clean up that code somewhat (Ulf
Hansson, Lina Iyer, Viresh Kumar).
- Fix minor issues in the powernv cpuidle driver and clean it up
(Anton Blanchard, Gautham Shenoy).
- Move the AnalyzeSuspend utility under tools/power/pm-graph/ and add
an analogous boot-profiling utility called AnalyzeBoot to it (Todd
Brandt).
- Add rk3328 support to the rockchip-io AVS (Adaptive Voltage
Scaling) driver (David Wu).
- Fix minor issues in the cpuidle core, the intel_pstate_tracer
utility, the devfreq framework and the PM core documentation
(Chanwoo Choi, Doug Smythies, Johan Hovold, Marcin Nowakowski)"
* tag 'pm-4.12-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (56 commits)
PM / runtime: Document autosuspend-helper side effects
PM / runtime: Fix autosuspend documentation
tools: power: pm-graph: Package makefile and man pages
tools: power: pm-graph: AnalyzeBoot v2.0
tools: power: pm-graph: AnalyzeSuspend v4.6
cpufreq: Add Tegra186 cpufreq driver
cpufreq: imx6q: Fix error handling code
cpufreq: imx6q: Set max suspend_freq to avoid changes during suspend
cpufreq: imx6q: Fix handling EPROBE_DEFER from regulator
cpuidle: powernv: Avoid a branch in the core snooze_loop() loop
cpuidle: powernv: Don't continually set thread priority in snooze_loop()
cpuidle: powernv: Don't bounce between low and very low thread priority
cpuidle: cpuidle-cps: remove unused variable
tools/power/x86/intel_pstate_tracer: Adjust directory ownership
cpufreq: schedutil: Use policy-dependent transition delays
cpufreq: schedutil: Reduce frequencies slower
PM / devfreq: Move struct devfreq_governor to devfreq directory
PM / Domains: Ignore domain-idle-states that are not compatible
cpufreq: intel_pstate: Add support for Gemini Lake
powernv-cpuidle: Validate DT property array size
...
Pull cgroup updates from Tejun Heo:
"Nothing major. Two notable fixes are Li's second stab at fixing the
long-standing race condition in the mount path and suppression of
spurious warning from cgroup_get(). All other changes are trivial"
* 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: mark cgroup_get() with __maybe_unused
cgroup: avoid attaching a cgroup root to two different superblocks, take 2
cgroup: fix spurious warnings on cgroup_is_dead() from cgroup_sk_alloc()
cgroup: move cgroup_subsys_state parent field for cache locality
cpuset: Remove cpuset_update_active_cpus()'s parameter.
cgroup: switch to BUG_ON()
cgroup: drop duplicate header nsproxy.h
kernel: convert css_set.refcount from atomic_t to refcount_t
kernel: convert cgroup_namespace.count from atomic_t to refcount_t
irq_time_read() returns the irqtime minus the ksoftirqd time. This
is necessary because irq_time_read() is used to substract the IRQ time
from the sum_exec_runtime of a task. If we were to include the softirq
time of ksoftirqd, this task would substract its own CPU time everytime
it updates ksoftirqd->sum_exec_runtime which would therefore never
progress.
But this behaviour got broken by:
a499a5a14d ("sched/cputime: Increment kcpustat directly on irqtime account")
... which now includes ksoftirqd softirq time in the time returned by
irq_time_read().
This has resulted in wrong ksoftirqd cputime reported to userspace
through /proc/stat and thus "top" not showing ksoftirqd when it should
after intense networking load.
ksoftirqd->stime happens to be correct but it gets scaled down by
sum_exec_runtime through task_cputime_adjusted().
To fix this, just account the strict IRQ time in a separate counter and
use it to report the IRQ time.
Reported-and-tested-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1493129448-5356-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, a call to schedule() acts as a Tasks RCU quiescent state
only if a context switch actually takes place. However, just the
call to schedule() guarantees that the calling task has moved off of
whatever tracing trampoline that it might have been one previously.
This commit therefore plumbs schedule()'s "preempt" parameter into
rcu_note_context_switch(), which then records the Tasks RCU quiescent
state, but only if this call to schedule() was -not- due to a preemption.
To avoid adding overhead to the common-case context-switch path,
this commit hides the rcu_note_context_switch() check under an existing
non-common-case check.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Make the schedutil governor take the initial (default) value of the
rate_limit_us sysfs attribute from the (new) transition_delay_us
policy parameter (to be set by the scaling driver).
That will allow scaling drivers to make schedutil use smaller default
values of rate_limit_us and reduce the default average time interval
between consecutive frequency changes.
Make intel_pstate set transition_delay_us to 500.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Now that we have a tool to generate the PELT constants in C form,
use its output as a separate header.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We truncate (and loose) the lower 10 bits of runtime in
___update_load_avg(), this means there's a consistent bias to
under-account tasks. This is esp. significant for small tasks.
Cure this by only forwarding last_update_time to the point we've
actually accounted for, leaving the remainder for the next time.
Reported-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Historically our periods (or p) argument in PELT denoted the number of
full periods (what is now d2). However recent patches have changed
this to the total decay (previously p+1), leading to a confusing
discrepancy between comments and code.
Try and clarify things by making periods (in code) and p (in comments)
be the same thing (again).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Paul noticed that in the (periods >= LOAD_AVG_MAX_N) case in
__accumulate_sum(), the returned contribution value (LOAD_AVG_MAX) is
incorrect.
This is because at this point, the decay_load() on the old state --
the first step in accumulate_sum() -- will not have resulted in 0, and
will therefore result in a sum larger than the maximum value of our
series. Obviously broken.
Note that:
decay_load(LOAD_AVG_MAX, LOAD_AVG_MAX_N) =
1 (345 / 32)
47742 * - ^ = ~27
2
Not to mention that any further contribution from the d3 segment (our
new period) would also push it over the maximum.
Solve this by noting that we can write our c2 term:
p
c2 = 1024 \Sum y^n
n=1
In terms of our maximum value:
inf inf p
max = 1024 \Sum y^n = 1024 ( \Sum y^n + \Sum y^n + y^0 )
n=0 n=p+1 n=1
Further note that:
inf inf inf
( \Sum y^n ) y^p = \Sum y^(n+p) = \Sum y^n
n=0 n=0 n=p
Combined that gives us:
p
c2 = 1024 \Sum y^n
n=1
inf inf
= 1024 ( \Sum y^n - \Sum y^n - y^0 )
n=0 n=p+1
= max - (max y^(p+1)) - 1024
Further simplify things by dealing with p=0 early on.
Reported-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Cc: linux-kernel@vger.kernel.org
Fixes: a481db34b9 ("sched/fair: Optimize ___update_sched_avg()")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The schedutil governor reduces frequencies too fast in some
situations which cases undesirable performance drops to
appear.
To address that issue, make schedutil reduce the frequency slower by
setting it to the average of the value chosen during the previous
iteration of governor computations and the new one coming from its
frequency selection formula.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=194963
Reported-by: John <john.ettedgui@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
In cpuset_update_active_cpus(), cpu_online isn't used anymore. Remove
it.
Signed-off-by: Rakib Mullick<rakib.mullick@gmail.com>
Acked-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
With the introduction of SCHED_DEADLINE the whole notion that priority
is a single number is gone, therefore the @prio argument to
rt_mutex_setprio() doesn't make sense anymore.
So rework the code to pass a pi_task instead.
Note this also fixes a problem with pi_top_task caching; previously we
would not set the pointer (call rt_mutex_update_top_task) if the
priority didn't change, this could lead to a stale pointer.
As for the XXX, I think its fine to use pi_task->prio, because if it
differs from waiter->prio, a PI chain update is immenent.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: xlpang@redhat.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170323150216.303827095@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
A crash happened while I was playing with deadline PI rtmutex.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
IP: [<ffffffff810eeb8f>] rt_mutex_get_top_task+0x1f/0x30
PGD 232a75067 PUD 230947067 PMD 0
Oops: 0000 [#1] SMP
CPU: 1 PID: 10994 Comm: a.out Not tainted
Call Trace:
[<ffffffff810b658c>] enqueue_task+0x2c/0x80
[<ffffffff810ba763>] activate_task+0x23/0x30
[<ffffffff810d0ab5>] pull_dl_task+0x1d5/0x260
[<ffffffff810d0be6>] pre_schedule_dl+0x16/0x20
[<ffffffff8164e783>] __schedule+0xd3/0x900
[<ffffffff8164efd9>] schedule+0x29/0x70
[<ffffffff8165035b>] __rt_mutex_slowlock+0x4b/0xc0
[<ffffffff81650501>] rt_mutex_slowlock+0xd1/0x190
[<ffffffff810eeb33>] rt_mutex_timed_lock+0x53/0x60
[<ffffffff810ecbfc>] futex_lock_pi.isra.18+0x28c/0x390
[<ffffffff810ed8b0>] do_futex+0x190/0x5b0
[<ffffffff810edd50>] SyS_futex+0x80/0x180
This is because rt_mutex_enqueue_pi() and rt_mutex_dequeue_pi()
are only protected by pi_lock when operating pi waiters, while
rt_mutex_get_top_task(), will access them with rq lock held but
not holding pi_lock.
In order to tackle it, we introduce new "pi_top_task" pointer
cached in task_struct, and add new rt_mutex_update_top_task()
to update its value, it can be called by rt_mutex_setprio()
which held both owner's pi_lock and rq lock. Thus "pi_top_task"
can be safely accessed by enqueue_task_dl() under rq lock.
Originally-From: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170323150216.157682758@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Pull scheduler fixes from Thomas Gleixner:
"This update provides:
- make the scheduler clock switch to unstable mode smooth so the
timestamps stay at microseconds granularity instead of switching to
tick granularity.
- unbreak perf test tsc by taking the new offset into account which
was added in order to proveide better sched clock continuity
- switching sched clock to unstable mode runs all clock related
computations which affect the sched clock output itself from a work
queue. In case of preemption sched clock uses half updated data and
provides wrong timestamps. Keep the math in the protected context
and delegate only the static key switch to workqueue context.
- remove a duplicate header include"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/headers: Remove duplicate #include <linux/sched/debug.h> line
sched/clock: Fix broken stable to unstable transfer
sched/clock, x86/perf: Fix "perf test tsc"
sched/clock: Fix clear_sched_clock_stable() preempt wobbly
The main PELT function ___update_load_avg(), which implements the
accumulation and progression of the geometric average series, is
implemented along the following lines for the scenario where the time
delta spans all 3 possible sections (see figure below):
1. add the remainder of the last incomplete period
2. decay old sum
3. accumulate new sum in full periods since last_update_time
4. accumulate the current incomplete period
5. update averages
Or:
d1 d2 d3
^ ^ ^
| | |
|<->|<----------------->|<--->|
... |---x---|------| ... |------|-----x (now)
load_sum' = (load_sum + weight * scale * d1) * y^(p+1) + (1,2)
p
weight * scale * 1024 * \Sum y^n + (3)
n=1
weight * scale * d3 * y^0 (4)
load_avg' = load_sum' / LOAD_AVG_MAX (5)
Where:
d1 - is the delta part completing the remainder of the last
incomplete period,
d2 - is the delta part spannind complete periods, and
d3 - is the delta part starting the current incomplete period.
We can simplify the code in two steps; the first step is to separate
the first term into new and old parts like:
(load_sum + weight * scale * d1) * y^(p+1) = load_sum * y^(p+1) +
weight * scale * d1 * y^(p+1)
Once we've done that, its easy to see that all new terms carry the
common factors:
weight * scale
If we factor those out, we arrive at the form:
load_sum' = load_sum * y^(p+1) +
weight * scale * (d1 * y^(p+1) +
p
1024 * \Sum y^n +
n=1
d3 * y^0)
Which results in a simpler, smaller and faster implementation.
Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: matt@codeblueprint.co.uk
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1486935863-25251-3-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The __update_load_avg() function is an __always_inline because its
used with constant propagation to generate different variants of the
code without having to duplicate it (which would be prone to bugs).
Explicitly instantiate the 3 variants.
Note that most of this is called from rather hot paths, so reducing
branches is good.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When it is determined that the clock is actually unstable, and
we switch from stable to unstable, the __clear_sched_clock_stable()
function is eventually called.
In this function we set gtod_offset so the following holds true:
sched_clock() + raw_offset == ktime_get_ns() + gtod_offset
But instead of getting the latest timestamps, we use the last values
from scd, so instead of sched_clock() we use scd->tick_raw, and
instead of ktime_get_ns() we use scd->tick_gtod.
However, later, when we use gtod_offset sched_clock_local() we do not
add it to scd->tick_gtod to calculate the correct clock value when we
determine the boundaries for min/max clocks.
This can result in tick granularity sched_clock() values, so fix it.
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hpa@zytor.com
Fixes: 5680d8094f ("sched/clock: Provide better clock continuity")
Link: http://lkml.kernel.org/r/1490214265-899964-2-git-send-email-pasha.tatashin@oracle.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If the child domain prefers tasks to go siblings, the local group could
end up pulling tasks to itself even if the local group is almost equally
loaded as the source group.
Lets assume a 4 core,smt==2 machine running 5 thread ebizzy workload.
Everytime, local group has capacity and source group has atleast 2 threads,
local group tries to pull the task. This causes the threads to constantly
move between different cores. This is even more profound if the cores have
more threads, like in Power 8, smt 8 mode.
Fix this by only allowing local group to pull a task, if the source group
has more number of tasks than the local group.
Here are the relevant perf stat numbers of a 22 core,smt 8 Power 8 machine.
Without patch:
Performance counter stats for 'ebizzy -t 22 -S 100' (5 runs):
1,440 context-switches # 0.001 K/sec ( +- 1.26% )
366 cpu-migrations # 0.000 K/sec ( +- 5.58% )
3,933 page-faults # 0.002 K/sec ( +- 11.08% )
Performance counter stats for 'ebizzy -t 48 -S 100' (5 runs):
6,287 context-switches # 0.001 K/sec ( +- 3.65% )
3,776 cpu-migrations # 0.001 K/sec ( +- 4.84% )
5,702 page-faults # 0.001 K/sec ( +- 9.36% )
Performance counter stats for 'ebizzy -t 96 -S 100' (5 runs):
8,776 context-switches # 0.001 K/sec ( +- 0.73% )
2,790 cpu-migrations # 0.000 K/sec ( +- 0.98% )
10,540 page-faults # 0.001 K/sec ( +- 3.12% )
With patch:
Performance counter stats for 'ebizzy -t 22 -S 100' (5 runs):
1,133 context-switches # 0.001 K/sec ( +- 4.72% )
123 cpu-migrations # 0.000 K/sec ( +- 3.42% )
3,858 page-faults # 0.002 K/sec ( +- 8.52% )
Performance counter stats for 'ebizzy -t 48 -S 100' (5 runs):
2,169 context-switches # 0.000 K/sec ( +- 6.19% )
189 cpu-migrations # 0.000 K/sec ( +- 12.75% )
5,917 page-faults # 0.001 K/sec ( +- 8.09% )
Performance counter stats for 'ebizzy -t 96 -S 100' (5 runs):
5,333 context-switches # 0.001 K/sec ( +- 5.91% )
506 cpu-migrations # 0.000 K/sec ( +- 3.35% )
10,792 page-faults # 0.001 K/sec ( +- 7.75% )
Which show that in these workloads CPU migrations get reduced significantly.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/1490205470-10249-1-git-send-email-srikar@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch fix spelling typos found in
Documentation/output/xml/driver-api/basics.xml.
It is because the xml file was generated from comments in source,
so I had to fix the comments.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
sugov_update_commit() calls trace_cpu_frequency() to record the
current CPU frequency if it has not changed in the fast switch case
to prevent utilities from getting confused (they may report that the
CPU is idle if the frequency has not been recorded for too long, for
example).
However, that may cause the tracepoint to be triggered quite often
for no real reason (if the frequency doesn't change, we will not
modify the last update time stamp and governor computations may
run again shortly when that happens), so don't do that (arguably, it
is done to work around a utilities bug anyway).
That allows code duplication in sugov_update_commit() to be reduced
somewhat too.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
A regression of the FTQ noise has been reported by Ying Huang,
on the following hardware:
8 threads Intel(R) Core(TM)i7-4770 CPU @ 3.40GHz with 8G memory
... which was caused by this commit:
commit 4e5160766f ("sched/fair: Propagate asynchrous detach")
The only part of the patch that can increase the noise is the update
of blocked load of group entity in update_blocked_averages().
We can optimize this call and skip the update of group entity if its load
and utilization are already null and there is no pending propagation of load
in the task group.
This optimization partly restores the noise score. A more agressive
optimization has been tried but has shown worse score.
Reported-by: ying.huang@linux.intel.com
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: ying.huang@intel.com
Fixes: 4e5160766f ("sched/fair: Propagate asynchrous detach")
Link: http://lkml.kernel.org/r/1489758442-2877-1-git-send-email-vincent.guittot@linaro.org
[ Fixed typos, improved layout. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
People reported that commit:
5680d8094f ("sched/clock: Provide better clock continuity")
broke "perf test tsc".
That commit added another offset to the reported clock value; so
take that into account when computing the provided offset values.
Reported-by: Adrian Hunter <adrian.hunter@intel.com>
Reported-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Tested-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 5680d8094f ("sched/clock: Provide better clock continuity")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Paul reported a problems with clear_sched_clock_stable(). Since we run
all of __clear_sched_clock_stable() from workqueue context, there's a
preempt problem.
Solve it by only running the static_key_disable() from workqueue.
Reported-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: fweisbec@gmail.com
Link: http://lkml.kernel.org/r/20170313124621.GA3328@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The way the schedutil governor uses the PELT metric causes it to
underestimate the CPU utilization in some cases.
That can be easily demonstrated by running kernel compilation on
a Sandy Bridge Intel processor, running turbostat in parallel with
it and looking at the values written to the MSR_IA32_PERF_CTL
register. Namely, the expected result would be that when all CPUs
were 100% busy, all of them would be requested to run in the maximum
P-state, but observation shows that this clearly isn't the case.
The CPUs run in the maximum P-state for a while and then are
requested to run slower and go back to the maximum P-state after
a while again. That causes the actual frequency of the processor to
visibly oscillate below the sustainable maximum in a jittery fashion
which clearly is not desirable.
That has been attributed to CPU utilization metric updates on task
migration that cause the total utilization value for the CPU to be
reduced by the utilization of the migrated task. If that happens,
the schedutil governor may see a CPU utilization reduction and will
attempt to reduce the CPU frequency accordingly right away. That
may be premature, though, for example if the system is generally
busy and there are other runnable tasks waiting to be run on that
CPU already.
This is unlikely to be an issue on systems where cpufreq policies are
shared between multiple CPUs, because in those cases the policy
utilization is computed as the maximum of the CPU utilization values
over the whole policy and if that turns out to be low, reducing the
frequency for the policy most likely is a good idea anyway. On
systems with one CPU per policy, however, it may affect performance
adversely and even lead to increased energy consumption in some cases.
On those systems it may be addressed by taking another utilization
metric into consideration, like whether or not the CPU whose
frequency is about to be reduced has been idle recently, because if
that's not the case, the CPU is likely to be busy in the near future
and its frequency should not be reduced.
To that end, use the counter of idle calls in the timekeeping code.
Namely, make the schedutil governor look at that counter for the
current CPU every time before its frequency is about to be reduced.
If the counter has not changed since the previous iteration of the
governor computations for that CPU, the CPU has been busy for all
that time and its frequency should not be decreased, so if the new
frequency would be lower than the one set previously, the governor
will skip the frequency update.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Joel Fernandes <joelaf@google.com>
sugov_start() only initializes struct sugov_cpu per-CPU structures
for shared policies, but it should do that for single-CPU policies too.
That in particular makes the IO-wait boost mechanism work in the
cases when cpufreq policies correspond to individual CPUs.
Fixes: 21ca6d2c52 (cpufreq: schedutil: Add iowait boosting)
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 4.9+ <stable@vger.kernel.org> # 4.9+
Add DEQUEUE_NOCLOCK to all places where we just did an
update_rq_clock() already.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of relying on deactivate_task() to call update_rq_clock() and
handling the case where it didn't happen (task_on_rq_queued),
unconditionally do update_rq_clock() and skip any further updates.
This also avoids a double update on deactivate_task() + ttwu_local().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since all tasks on the wake_list are woken under a single rq->lock
avoid calling update_rq_clock() for each task.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In all cases, ENQUEUE_RESTORE should also have ENQUEUE_NOCLOCK because
DEQUEUE_SAVE will have done an update_rq_clock().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently {en,de}queue_task() do an unconditional update_rq_clock().
However since we want to avoid duplicate updates, so that each
rq->lock section appears atomic in time, we need to be able to skip
these clock updates.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The missing update_rq_clock() check can work with partial rq->lock
wrappery, since a missing wrapper can cause the warning to not be
emitted when it should have, but cannot cause the warning to trigger
when it should not have.
The duplicate update_rq_clock() check however can cause false warnings
to trigger. Therefore add more comprehensive rq->lock wrappery.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that we have no missing calls, add a warning to find multiple
calls.
By having only a single update_rq_clock() call per rq-lock section,
the section appears 'atomic' wrt time.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While looking into optimizations for the RT scheduler IPI logic, I realized
that the comments are lacking to describe it efficiently. It deserves a
lengthy description describing its design.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Clark Williams <williams@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170228155030.30c69068@gandalf.local.home
[ Small typographical edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
I was testing Daniel's changes with his test case, and tweaked it a
little. Instead of having the runtime equal to the deadline, I
increased the deadline ten fold.
Daniel's test case had:
attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */
attr.sched_deadline = 2 * 1000 * 1000; /* 2 ms */
attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */
To make it more interesting, I changed it to:
attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */
attr.sched_deadline = 20 * 1000 * 1000; /* 20 ms */
attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */
The results were rather surprising. The behavior that Daniel's patch
was fixing came back. The task started using much more than .1% of the
CPU. More like 20%.
Looking into this I found that it was due to the dl_entity_overflow()
constantly returning true. That's because it uses the relative period
against relative runtime vs the absolute deadline against absolute
runtime.
runtime / (deadline - t) > dl_runtime / dl_period
There's even a comment mentioning this, and saying that when relative
deadline equals relative period, that the equation is the same as using
deadline instead of period. That comment is backwards! What we really
want is:
runtime / (deadline - t) > dl_runtime / dl_deadline
We care about if the runtime can make its deadline, not its period. And
then we can say "when the deadline equals the period, the equation is
the same as using dl_period instead of dl_deadline".
After correcting this, now when the task gets enqueued, it can throttle
correctly, and Daniel's fix to the throttling of sleeping deadline
tasks works even when the runtime and deadline are not the same.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/02135a27f1ae3fe5fd032568a5a2f370e190e8d7.1488392936.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
During the activation, CBS checks if it can reuse the current task's
runtime and period. If the deadline of the task is in the past, CBS
cannot use the runtime, and so it replenishes the task. This rule
works fine for implicit deadline tasks (deadline == period), and the
CBS was designed for implicit deadline tasks. However, a task with
constrained deadline (deadine < period) might be awakened after the
deadline, but before the next period. In this case, replenishing the
task would allow it to run for runtime / deadline. As in this case
deadline < period, CBS enables a task to run for more than the
runtime / period. In a very loaded system, this can cause a domino
effect, making other tasks miss their deadlines.
To avoid this problem, in the activation of a constrained deadline
task after the deadline but before the next period, throttle the
task and set the replenishing timer to the begin of the next period,
unless it is boosted.
Reproducer:
--------------- %< ---------------
int main (int argc, char **argv)
{
int ret;
int flags = 0;
unsigned long l = 0;
struct timespec ts;
struct sched_attr attr;
memset(&attr, 0, sizeof(attr));
attr.size = sizeof(attr);
attr.sched_policy = SCHED_DEADLINE;
attr.sched_runtime = 2 * 1000 * 1000; /* 2 ms */
attr.sched_deadline = 2 * 1000 * 1000; /* 2 ms */
attr.sched_period = 2 * 1000 * 1000 * 1000; /* 2 s */
ts.tv_sec = 0;
ts.tv_nsec = 2000 * 1000; /* 2 ms */
ret = sched_setattr(0, &attr, flags);
if (ret < 0) {
perror("sched_setattr");
exit(-1);
}
for(;;) {
/* XXX: you may need to adjust the loop */
for (l = 0; l < 150000; l++);
/*
* The ideia is to go to sleep right before the deadline
* and then wake up before the next period to receive
* a new replenishment.
*/
nanosleep(&ts, NULL);
}
exit(0);
}
--------------- >% ---------------
On my box, this reproducer uses almost 50% of the CPU time, which is
obviously wrong for a task with 2/2000 reservation.
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/edf58354e01db46bf42df8d2dd32418833f68c89.1488392936.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, the replenishment timer is set to fire at the deadline
of a task. Although that works for implicit deadline tasks because the
deadline is equals to the begin of the next period, that is not correct
for constrained deadline tasks (deadline < period).
For instance:
f.c:
--------------- %< ---------------
int main (void)
{
for(;;);
}
--------------- >% ---------------
# gcc -o f f.c
# trace-cmd record -e sched:sched_switch \
-e syscalls:sys_exit_sched_setattr \
chrt -d --sched-runtime 490000000 \
--sched-deadline 500000000 \
--sched-period 1000000000 0 ./f
# trace-cmd report | grep "{pid of ./f}"
After setting parameters, the task is replenished and continue running
until being throttled:
f-11295 [003] 13322.113776: sys_exit_sched_setattr: 0x0
The task is throttled after running 492318 ms, as expected:
f-11295 [003] 13322.606094: sched_switch: f:11295 [-1] R ==> watchdog/3:32 [0]
But then, the task is replenished 500719 ms after the first
replenishment:
<idle>-0 [003] 13322.614495: sched_switch: swapper/3:0 [120] R ==> f:11295 [-1]
Running for 490277 ms:
f-11295 [003] 13323.104772: sched_switch: f:11295 [-1] R ==> swapper/3:0 [120]
Hence, in the first period, the task runs 2 * runtime, and that is a bug.
During the first replenishment, the next deadline is set one period away.
So the runtime / period starts to be respected. However, as the second
replenishment took place in the wrong instant, the next replenishment
will also be held in a wrong instant of time. Rather than occurring in
the nth period away from the first activation, it is taking place
in the (nth period - relative deadline).
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Luca Abeni <luca.abeni@santannapisa.it>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Link: http://lkml.kernel.org/r/ac50d89887c25285b47465638354b63362f8adff.1488392936.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
'calc_load_update' is accessed without any kind of locking and there's
a clear assumption in the code that only a single value is read or
written.
Make this explicit by using READ_ONCE() and WRITE_ONCE(), and avoid
unintentionally seeing multiple values, or having the load/stores
split.
Technically the loads in calc_global_*() don't require this since
those are the only functions that update 'calc_load_update', but I've
added the READ_ONCE() for consistency.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20170217120731.11868-3-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If we crossed a sample window while in NO_HZ we will add LOAD_FREQ to
the pending sample window time on exit, setting the next update not
one window into the future, but two.
This situation on exiting NO_HZ is described by:
this_rq->calc_load_update < jiffies < calc_load_update
In this scenario, what we should be doing is:
this_rq->calc_load_update = calc_load_update [ next window ]
But what we actually do is:
this_rq->calc_load_update = calc_load_update + LOAD_FREQ [ next+1 window ]
This has the effect of delaying load average updates for potentially
up to ~9seconds.
This can result in huge spikes in the load average values due to
per-cpu uninterruptible task counts being out of sync when accumulated
across all CPUs.
It's safe to update the per-cpu active count if we wake between sample
windows because any load that we left in 'calc_load_idle' will have
been zero'd when the idle load was folded in calc_global_load().
This issue is easy to reproduce before,
commit 9d89c257df ("sched/fair: Rewrite runnable load and utilization average tracking")
just by forking short-lived process pipelines built from ps(1) and
grep(1) in a loop. I'm unable to reproduce the spikes after that
commit, but the bug still seems to be present from code review.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Fixes: commit 5167e8d ("sched/nohz: Rewrite and fix load-avg computation -- again")
Link: http://lkml.kernel.org/r/20170217120731.11868-2-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The following warning can be triggered by hot-unplugging the CPU
on which an active SCHED_DEADLINE task is running on:
------------[ cut here ]------------
WARNING: CPU: 7 PID: 0 at kernel/sched/sched.h:833 replenish_dl_entity+0x71e/0xc40
rq->clock_update_flags < RQCF_ACT_SKIP
CPU: 7 PID: 0 Comm: swapper/7 Tainted: G B 4.11.0-rc1+ #24
Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY, BIOS FBKTC1AUS 02/16/2016
Call Trace:
<IRQ>
dump_stack+0x85/0xc4
__warn+0x172/0x1b0
warn_slowpath_fmt+0xb4/0xf0
? __warn+0x1b0/0x1b0
? debug_check_no_locks_freed+0x2c0/0x2c0
? cpudl_set+0x3d/0x2b0
replenish_dl_entity+0x71e/0xc40
enqueue_task_dl+0x2ea/0x12e0
? dl_task_timer+0x777/0x990
? __hrtimer_run_queues+0x270/0xa50
dl_task_timer+0x316/0x990
? enqueue_task_dl+0x12e0/0x12e0
? enqueue_task_dl+0x12e0/0x12e0
__hrtimer_run_queues+0x270/0xa50
? hrtimer_cancel+0x20/0x20
? hrtimer_interrupt+0x119/0x600
hrtimer_interrupt+0x19c/0x600
? trace_hardirqs_off+0xd/0x10
local_apic_timer_interrupt+0x74/0xe0
smp_apic_timer_interrupt+0x76/0xa0
apic_timer_interrupt+0x93/0xa0
The DL task will be migrated to a suitable later deadline rq once the DL
timer fires and currnet rq is offline. The rq clock of the new rq should
be updated. This patch fixes it by updating the rq clock after holding
the new rq's rq lock.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1488865888-15894-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The loop in sugov_next_freq_shared() contains an if block to skip the
loop for the current CPU. This turns out to be an unnecessary
conditional in the scheduler's hot-path for every CPU in the policy.
It would be better to drop the conditional and make the loop treat all
the CPUs in the same way. That would eliminate the need of calling
sugov_iowait_boost() at the top of the routine.
To keep the code optimized to return early if the current CPU has RT/DL
flags set, move the flags check to sugov_update_shared() instead in
order to avoid the function call entirely.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The rate_limit_us tunable is intended to reduce the possible overhead
from running the schedutil governor. However, that overhead can be
divided into two separate parts: the governor computations and the
invocation of the scaling driver to set the CPU frequency. The latter
is where the real overhead comes from. The former is much less
expensive in terms of execution time and running it every time the
governor callback is invoked by the scheduler, after rate_limit_us
interval has passed since the last frequency update, would not be a
problem.
For this reason, redefine the rate_limit_us tunable so that it means the
minimum time that has to pass between two consecutive invocations of the
scaling driver by the schedutil governor (to set the CPU frequency).
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
- Three fixes for intel_pstate problems related to the passive
mode (in which it acts as a regular cpufreq scaling driver), two
for the handling of global P-state limits and one for the handling
of the cpu_frequency tracepoint in that mode (Rafael Wysocki).
- Three fixes for the handling of P-state limits in intel_pstate in
the active mode (Rafael Wysocki).
- Introduction of a new cpufreq.off=1 kernel command line argument
that will disable cpufreq entirely if passed to the kernel and
is simply hooked up to the existing code used by Xen (Len Brown).
- Fix for the schedutil cpufreq governor to prevent it from using
stale raw frequency values in configurations with mutiple CPUs
sharing one policy object and a cleanup for it reducing its
overhead slightly (Viresh Kumar).
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Merge tag 'pm-4.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management fixes from Rafael Wysocki:
"These fix several issues in the intel_pstate driver and one issue in
the schedutil cpufreq governor, clean up that governor a bit and hook
up existing code for disabling cpufreq to a new kernel command line
option.
Specifics:
- Three fixes for intel_pstate problems related to the passive mode
(in which it acts as a regular cpufreq scaling driver), two for the
handling of global P-state limits and one for the handling of the
cpu_frequency tracepoint in that mode (Rafael Wysocki).
- Three fixes for the handling of P-state limits in intel_pstate in
the active mode (Rafael Wysocki).
- Introduction of a new cpufreq.off=1 kernel command line argument
that will disable cpufreq entirely if passed to the kernel and is
simply hooked up to the existing code used by Xen (Len Brown).
- Fix for the schedutil cpufreq governor to prevent it from using
stale raw frequency values in configurations with mutiple CPUs
sharing one policy object and a cleanup for it reducing its
overhead slightly (Viresh Kumar)"
* tag 'pm-4.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
cpufreq: intel_pstate: Do not reinit performance limits in ->setpolicy
cpufreq: intel_pstate: Fix intel_pstate_verify_policy()
cpufreq: intel_pstate: Fix global settings in active mode
cpufreq: Add the "cpufreq.off=1" cmdline option
cpufreq: schedutil: Pass sg_policy to get_next_freq()
cpufreq: schedutil: move cached_raw_freq to struct sugov_policy
cpufreq: intel_pstate: Avoid triggering cpu_frequency tracepoint unnecessarily
cpufreq: intel_pstate: Fix intel_cpufreq_verify_policy()
cpufreq: intel_pstate: Do not use performance_limits in passive mode
The scheduler header file split and cleanups ended up exposing a few
nasty header file dependencies, and in particular it showed how we in
<linux/wait.h> ended up depending on "signal_pending()", which now comes
from <linux/sched/signal.h>.
That's a very subtle and annoying dependency, which already caused a
semantic merge conflict (see commit e58bc92783 "Pull overlayfs updates
from Miklos Szeredi", which added that fixup in the merge commit).
It turns out that we can avoid this dependency _and_ improve code
generation by moving the guts of the fairly nasty helper #define
__wait_event_interruptible_locked() to out-of-line code. The code that
includes the signal_pending() check is all in the slow-path where we
actually go to sleep waiting for the event anyway, so using a helper
function is the right thing to do.
Using a helper function is also what we already did for the non-locked
versions, see the "__wait_event*()" macros and the "prepare_to_wait*()"
set of helper functions.
We might want to try to unify all these macro games, we have a _lot_ of
subtly different wait-event loops. But this is the minimal patch to fix
the annoying header dependency.
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change livepatch to use a basic per-task consistency model. This is the
foundation which will eventually enable us to patch those ~10% of
security patches which change function or data semantics. This is the
biggest remaining piece needed to make livepatch more generally useful.
This code stems from the design proposal made by Vojtech [1] in November
2014. It's a hybrid of kGraft and kpatch: it uses kGraft's per-task
consistency and syscall barrier switching combined with kpatch's stack
trace switching. There are also a number of fallback options which make
it quite flexible.
Patches are applied on a per-task basis, when the task is deemed safe to
switch over. When a patch is enabled, livepatch enters into a
transition state where tasks are converging to the patched state.
Usually this transition state can complete in a few seconds. The same
sequence occurs when a patch is disabled, except the tasks converge from
the patched state to the unpatched state.
An interrupt handler inherits the patched state of the task it
interrupts. The same is true for forked tasks: the child inherits the
patched state of the parent.
Livepatch uses several complementary approaches to determine when it's
safe to patch tasks:
1. The first and most effective approach is stack checking of sleeping
tasks. If no affected functions are on the stack of a given task,
the task is patched. In most cases this will patch most or all of
the tasks on the first try. Otherwise it'll keep trying
periodically. This option is only available if the architecture has
reliable stacks (HAVE_RELIABLE_STACKTRACE).
2. The second approach, if needed, is kernel exit switching. A
task is switched when it returns to user space from a system call, a
user space IRQ, or a signal. It's useful in the following cases:
a) Patching I/O-bound user tasks which are sleeping on an affected
function. In this case you have to send SIGSTOP and SIGCONT to
force it to exit the kernel and be patched.
b) Patching CPU-bound user tasks. If the task is highly CPU-bound
then it will get patched the next time it gets interrupted by an
IRQ.
c) In the future it could be useful for applying patches for
architectures which don't yet have HAVE_RELIABLE_STACKTRACE. In
this case you would have to signal most of the tasks on the
system. However this isn't supported yet because there's
currently no way to patch kthreads without
HAVE_RELIABLE_STACKTRACE.
3. For idle "swapper" tasks, since they don't ever exit the kernel, they
instead have a klp_update_patch_state() call in the idle loop which
allows them to be patched before the CPU enters the idle state.
(Note there's not yet such an approach for kthreads.)
All the above approaches may be skipped by setting the 'immediate' flag
in the 'klp_patch' struct, which will disable per-task consistency and
patch all tasks immediately. This can be useful if the patch doesn't
change any function or data semantics. Note that, even with this flag
set, it's possible that some tasks may still be running with an old
version of the function, until that function returns.
There's also an 'immediate' flag in the 'klp_func' struct which allows
you to specify that certain functions in the patch can be applied
without per-task consistency. This might be useful if you want to patch
a common function like schedule(), and the function change doesn't need
consistency but the rest of the patch does.
For architectures which don't have HAVE_RELIABLE_STACKTRACE, the user
must set patch->immediate which causes all tasks to be patched
immediately. This option should be used with care, only when the patch
doesn't change any function or data semantics.
In the future, architectures which don't have HAVE_RELIABLE_STACKTRACE
may be allowed to use per-task consistency if we can come up with
another way to patch kthreads.
The /sys/kernel/livepatch/<patch>/transition file shows whether a patch
is in transition. Only a single patch (the topmost patch on the stack)
can be in transition at a given time. A patch can remain in transition
indefinitely, if any of the tasks are stuck in the initial patch state.
A transition can be reversed and effectively canceled by writing the
opposite value to the /sys/kernel/livepatch/<patch>/enabled file while
the transition is in progress. Then all the tasks will attempt to
converge back to the original patch state.
[1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Ingo Molnar <mingo@kernel.org> # for the scheduler changes
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Pull scheduler fixes from Ingo Molnar:
"A fix for KVM's scheduler clock which (erroneously) was always marked
unstable, a fix for RT/DL load balancing, plus latency fixes"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface
sched/core: Fix pick_next_task() for RT,DL
sched/fair: Make select_idle_cpu() more aggressive
get_next_freq() uses sg_cpu only to get sg_policy, which the callers of
get_next_freq() already have. Pass sg_policy instead of sg_cpu to
get_next_freq(), to make it more efficient.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
cached_raw_freq applies to the entire cpufreq policy and not individual
CPUs. Apart from wasting per-cpu memory, it is actually wrong to keep it
in struct sugov_cpu as we may end up comparing next_freq with a stale
cached_raw_freq of a random CPU.
Move cached_raw_freq to struct sugov_policy.
Fixes: 5cbea46984 (cpufreq: schedutil: map raw required frequency to driver frequency)
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Move cputime related functionality out of <linux/sched.h>, as most code
that includes <linux/sched.h> does not use that functionality.
Move data types that are not included in task_struct directly to
the signal definitions, into <linux/sched/signal.h>.
Also merge the (small) existing <linux/cputime.h> header into <linux/sched/cputime.h>.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pavan noticed that the following commit:
49ee576809 ("sched/core: Optimize pick_next_task() for idle_sched_class")
... broke RT,DL balancing by robbing them of the opportinty to do new-'idle'
balancing when their last runnable task (on that runqueue) goes away.
Reported-by: Pavan Kondeti <pkondeti@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 49ee576809 ("sched/core: Optimize pick_next_task() for idle_sched_class")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Kitsunyan reported desktop latency issues on his Celeron 887 because
of commit:
1b568f0aab ("sched/core: Optimize SCHED_SMT")
... even though his CPU doesn't do SMT.
The effect of running the SMT code on a !SMT part is basically a more
aggressive select_idle_cpu(). Removing the avg condition fixed things
for him.
I also know FB likes this test gone, even though other workloads like
having it.
For now, take it out by default, until we get a better idea.
Reported-by: kitsunyan <kitsunyan@inbox.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
But first introduce a trivial header and update usage sites.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Introduce a trivial, mostly empty <linux/sched/cputime.h> header
to prepare for the moving of cputime functionality out of sched.h.
Update all code that relies on these facilities.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
But first update the code that uses these facilities with the
new header.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Update code that relied on sched.h including various MM types for them.
This will allow us to remove the <linux/mm_types.h> include from <linux/sched.h>.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/task.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/task.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/hotplug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/hotplug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/debug.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/debug.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/nohz.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/nohz.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/stat.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/stat.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Recent header reorganizations unearthed this hidden dependency:
kernel/sched/core.c:199:25: error: 'paravirt_steal_rq_enabled' undeclared (first use in this function)
kernel/sched/core.c:200:11: error: implicit declaration of function 'paravirt_steal_clock' [-Werror=implicit-function-declaration]
So move the asm/paravirt.h include from kernel/sched/cpuclock.c to kernel/sched/sched.h.
( NOTE: We do this change before doing the changes that introduce the build failure,
so the series remains fully bisectable. )
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/numa_balancing.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/numa_balancing.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/cpufreq.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/cpufreq.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to move softlockup APIs out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
<linux/nmi.h> already includes <linux/sched.h>.
Include the <linux/nmi.h> header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/mm.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/mm.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
The APIs that are going to be moved first are:
mm_alloc()
__mmdrop()
mmdrop()
mmdrop_async_fn()
mmdrop_async()
mmget_not_zero()
mmput()
mmput_async()
get_task_mm()
mm_access()
mm_release()
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/autogroup.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/autogroup.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/loadavg.h> out of <linux/sched.h>, which
will have to be picked up from a couple of .c files.
Create a trivial placeholder <linux/sched/topology.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to move scheduler ABI details to <uapi/linux/sched/types.h>,
which will be used from a number of .c files.
Create empty placeholder header that maps to <linux/types.h>.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/clock.h> out of <linux/sched.h>, which
will have to be picked up from other headers and .c files.
Create a trivial placeholder <linux/sched/clock.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/wake_q.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/wake_q.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/idle.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/idle.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We are going to split <linux/sched/topology.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/topology.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So rcupdate.h is a pretty complex header, in particular it includes
<linux/completion.h> which includes <linux/wait.h> - creating a
dependency that includes <linux/wait.h> in <linux/sched.h>,
which prevents the isolation of <linux/sched.h> from the derived
<linux/wait.h> header.
Solve part of the problem by decoupling rcupdate.h from completions:
this can be done by separating out the rcu_synchronize types and APIs,
and updating their usage sites.
Since this is a mostly RCU-internal types this will not just simplify
<linux/sched.h>'s dependencies, but will make all the hundreds of
.c files that include rcupdate.h but not completions or wait.h build
faster.
( For rcutiny this means that two dependent APIs have to be uninlined,
but that shouldn't be much of a problem as they are rare variants. )
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
tsk_nr_cpus_allowed() too is a pretty pointless wrapper that
is not used consistently and which makes the code both harder
to read and longer as well.
So remove it - this also shrinks <linux/sched.h> a bit.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
So the original intention of tsk_cpus_allowed() was to 'future-proof'
the field - but it's pretty ineffectual at that, because half of
the code uses ->cpus_allowed directly ...
Also, the wrapper makes the code longer than the original expression!
So just get rid of it. This also shrinks <linux/sched.h> a bit.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
It's defined in <linux/sched.h>, but nothing outside the scheduler
uses it - so move it to the sched/core.c usage site.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The length of TASK_STATE_TO_CHAR_STR was still checked using the old
link-time manual error method - convert it to BUILD_BUG_ON(). This
has a couple of advantages:
- it's more obvious what's going on
- it reduces the size and complexity of <linux/sched.h>
- BUILD_BUG_ON() will fail during compilation, with a clearer
error message than the link time assert.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Ingo Molnar:
"Two rq-clock warnings related fixes, plus a cgroups related crash fix"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/cgroup: Move sched_online_group() back into css_online() to fix crash
sched/fair: Update rq clock before changing a task's CPU affinity
sched/core: Fix update_rq_clock() splat on hotplug (and suspend/resume)
Apart from adding the helper function itself, the rest of the kernel is
converted mechanically using:
git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)->mm_count);/mmgrab\(\1\);/'
git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)\.mm_count);/mmgrab\(\&\1\);/'
This is needed for a later patch that hooks into the helper, but might
be a worthwhile cleanup on its own.
(Michal Hocko provided most of the kerneldoc comment.)
Link: http://lkml.kernel.org/r/20161218123229.22952-1-vegard.nossum@oracle.com
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit:
2f5177f0fd ("sched/cgroup: Fix/cleanup cgroup teardown/init")
.. moved sched_online_group() from css_online() to css_alloc().
It exposes half-baked task group into global lists before initializing
generic cgroup stuff.
LTP testcase (third in cgroup_regression_test) written for testing
similar race in kernels 2.6.26-2.6.28 easily triggers this oops:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: kernfs_path_from_node_locked+0x260/0x320
CPU: 1 PID: 30346 Comm: cat Not tainted 4.10.0-rc5-test #4
Call Trace:
? kernfs_path_from_node+0x4f/0x60
kernfs_path_from_node+0x3e/0x60
print_rt_rq+0x44/0x2b0
print_rt_stats+0x7a/0xd0
print_cpu+0x2fc/0xe80
? __might_sleep+0x4a/0x80
sched_debug_show+0x17/0x30
seq_read+0xf2/0x3b0
proc_reg_read+0x42/0x70
__vfs_read+0x28/0x130
? security_file_permission+0x9b/0xc0
? rw_verify_area+0x4e/0xb0
vfs_read+0xa5/0x170
SyS_read+0x46/0xa0
entry_SYSCALL_64_fastpath+0x1e/0xad
Here the task group is already linked into the global RCU-protected 'task_groups'
list, but the css->cgroup pointer is still NULL.
This patch reverts this chunk and moves online back to css_online().
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 2f5177f0fd ("sched/cgroup: Fix/cleanup cgroup teardown/init")
Link: http://lkml.kernel.org/r/148655324740.424917.5302984537258726349.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is triggered during boot when CONFIG_SCHED_DEBUG is enabled:
------------[ cut here ]------------
WARNING: CPU: 6 PID: 81 at kernel/sched/sched.h:812 set_next_entity+0x11d/0x380
rq->clock_update_flags < RQCF_ACT_SKIP
CPU: 6 PID: 81 Comm: torture_shuffle Not tainted 4.10.0+ #1
Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY, BIOS FBKTC1AUS 02/16/2016
Call Trace:
dump_stack+0x85/0xc2
__warn+0xcb/0xf0
warn_slowpath_fmt+0x5f/0x80
set_next_entity+0x11d/0x380
set_curr_task_fair+0x2b/0x60
do_set_cpus_allowed+0x139/0x180
__set_cpus_allowed_ptr+0x113/0x260
set_cpus_allowed_ptr+0x10/0x20
torture_shuffle+0xfd/0x180
kthread+0x10f/0x150
? torture_shutdown_init+0x60/0x60
? kthread_create_on_node+0x60/0x60
ret_from_fork+0x31/0x40
---[ end trace dd94d92344cea9c6 ]---
The task is running && !queued, so there is no rq clock update before calling
set_curr_task().
This patch fixes it by updating rq clock after holding rq->lock/pi_lock
just as what other dequeue + put_prev + enqueue + set_curr story does.
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1487749975-5994-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The hotplug code still triggers the warning about using a stale
rq->clock value.
Fix things up to actually run update_rq_clock() in a place where we
record the 'UPDATED' flag, and then modify the annotation to retain
this flag over the rq->lock fiddling that happens as a result of
actually migrating all the tasks elsewhere.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Tested-by: Mike Galbraith <efault@gmx.de>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ross Zwisler <zwisler@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 4d25b35ea3 ("sched/fair: Restore previous rq_flags when migrating tasks in hotplug")
Link: http://lkml.kernel.org/r/20170202155506.GX6515@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 004172bdad ("sched/core: Remove unnecessary #include headers")
removed the inclusion of asm/paravirt.h which is used to get
declarations of paravirt_steal_rq_enabled and paravirt_steal_clock.
It is implicitly included on x86 but not on arm and arm64 breaking the
build if paravirtualization is used. Since things from that header are
used directly fix the build by putting the direct inclusion back.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull scheduler updates from Ingo Molnar:
"The main changes in this (fairly busy) cycle were:
- There was a class of scheduler bugs related to forgetting to update
the rq-clock timestamp which can cause weird and hard to debug
problems, so there's a new debug facility for this: which uncovered
a whole lot of bugs which convinced us that we want to keep the
debug facility.
(Peter Zijlstra, Matt Fleming)
- Various cputime related updates: eliminate cputime and use u64
nanoseconds directly, simplify and improve the arch interfaces,
implement delayed accounting more widely, etc. - (Frederic
Weisbecker)
- Move code around for better structure plus cleanups (Ingo Molnar)
- Move IO schedule accounting deeper into the scheduler plus related
changes to improve the situation (Tejun Heo)
- ... plus a round of sched/rt and sched/deadline fixes, plus other
fixes, updats and cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (85 commits)
sched/core: Remove unlikely() annotation from sched_move_task()
sched/autogroup: Rename auto_group.[ch] to autogroup.[ch]
sched/topology: Split out scheduler topology code from core.c into topology.c
sched/core: Remove unnecessary #include headers
sched/rq_clock: Consolidate the ordering of the rq_clock methods
delayacct: Include <uapi/linux/taskstats.h>
sched/core: Clean up comments
sched/rt: Show the 'sched_rr_timeslice' SCHED_RR timeslice tuning knob in milliseconds
sched/clock: Add dummy clear_sched_clock_stable() stub function
sched/cputime: Remove generic asm headers
sched/cputime: Remove unused nsec_to_cputime()
s390, sched/cputime: Remove unused cputime definitions
powerpc, sched/cputime: Remove unused cputime definitions
s390, sched/cputime: Make arch_cpu_idle_time() to return nsecs
ia64, sched/cputime: Remove unused cputime definitions
ia64: Convert vtime to use nsec units directly
ia64, sched/cputime: Move the nsecs based cputime headers to the last arch using it
sched/cputime: Remove jiffies based cputime
sched/cputime, vtime: Return nsecs instead of cputime_t to account
sched/cputime: Complete nsec conversion of tick based accounting
...
The check for 'running' in sched_move_task() has an unlikely() around it. That
is, it is unlikely that the task being moved is running. That use to be
true. But with a couple of recent updates, it is now likely that the task
will be running.
The first change came from ea86cb4b76 ("sched/cgroup: Fix
cpu_cgroup_fork() handling") that moved around the use case of
sched_move_task() in do_fork() where the call is now done after the task is
woken (hence it is running).
The second change came from 8e5bfa8c1f ("sched/autogroup: Do not use
autogroup->tg in zombie threads") where sched_move_task() is called by the
exit path, by the task that is exiting. Hence it too is running.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20170206110426.27ca6426@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The names are all 'autogroup', not 'auto_group' - so rename
the kernel/sched/auto_group.[ch] to match the existing
nomenclature.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Over the years sched/core.c accumulated over 50 #include lines,
40 of which are superfluous. (!)
Removing them decreases the preprocessed .c file (.i) size noticeably:
triton:~/tip> wc -l kernel/sched/core.i
Before: 76387 kernel/sched/core.i
After: 75896 kernel/sched/core.i
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
update_rq_clock_task() and update_rq_clock() we unnecessarily
spread across core.c, requiring an extra prototype line.
Move them next to each other and in the proper order.
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Refresh the comments in the core scheduler code:
- Capitalize sentences consistently
- Capitalize 'CPU' consistently
- ... and other small details.
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We added the 'sched_rr_timeslice_ms' SCHED_RR tuning knob in this commit:
ce0dbbbb30 ("sched/rt: Add a tuning knob to allow changing SCHED_RR timeslice")
... which name suggests to users that it's in milliseconds, while in reality
it's being set in milliseconds but the result is shown in jiffies.
This is obviously confusing when HZ is not 1000, it makes it appear like the
value set failed, such as HZ=100:
root# echo 100 > /proc/sys/kernel/sched_rr_timeslice_ms
root# cat /proc/sys/kernel/sched_rr_timeslice_ms
10
Fix this to be milliseconds all around.
Signed-off-by: Shile Zhang <shile.zhang@nokia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1485612049-20923-1-git-send-email-shile.zhang@nokia.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Turn the full dynticks cputime clock source to return nsec while keeping
its very internals jiffies based for performance reasons.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-27-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is the final step toward tick based cputime conversion. Now that
the whole cputime accounting engine accounts in nsecs, we can convert the
very source of the cputime to account in nsecs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-26-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is one more step toward converting cputime accounting to pure nsecs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-25-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is one more step toward converting cputime accounting to pure nsecs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-24-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is one more step toward converting cputime accounting to pure nsecs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-23-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This is one more step toward converting cputime accounting to pure nsecs.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-22-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Use the new nsec based cputime accessors as part of the whole cputime
conversion from cputime_t to nsecs.
Also convert posix-cpu-timers to use nsec based internal counters to
simplify it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-19-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The irqtime is accounted is nsecs and stored in
cpu_irq_time.hardirq_time and cpu_irq_time.softirq_time. Once the
accumulated amount reaches a new jiffy, this one gets accounted to the
kcpustat.
This was necessary when kcpustat was stored in cputime_t, which could at
worst have jiffies granularity. But now kcpustat is stored in nsecs
so this whole discretization game with temporary irqtime storage has
become unnecessary.
We can now directly account the irqtime to the kcpustat.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-17-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that most cputime readers use the transition API which return the
task cputime in old style cputime_t, we can safely store the cputime in
nsecs. This will eventually make cputime statistics less opaque and more
granular. Back and forth convertions between cputime_t and nsecs in order
to deal with cputime_t random granularity won't be needed anymore.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-8-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
cputime_t is being obsolete and replaced by nsecs units in order to make
internal timestamps less opaque and more granular.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Kernel CPU stats are stored in cputime_t which is an architecture
defined type, and hence a bit opaque and requiring accessors and mutators
for any operation.
Converting them to nsecs simplifies the code and is one step toward
the removal of cputime_t in the core code.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1485832191-26889-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since the change in commit:
fd7a4bed18 ("sched, rt: Convert switched_{from, to}_rt() / prio_changed_rt() to balance callbacks")
... we don't reschedule a task under certain circumstances:
Lets say task-A, SCHED_OTHER, is running on CPU0 (and it may run only on
CPU0) and holds a PI lock. This task is removed from the CPU because it
used up its time slice and another SCHED_OTHER task is running. Task-B on
CPU1 runs at RT priority and asks for the lock owned by task-A. This
results in a priority boost for task-A. Task-B goes to sleep until the
lock has been made available. Task-A is already runnable (but not active),
so it receives no wake up.
The reality now is that task-A gets on the CPU once the scheduler decides
to remove the current task despite the fact that a high priority task is
enqueued and waiting. This may take a long time.
The desired behaviour is that CPU0 immediately reschedules after the
priority boost which made task-A the task with the lowest priority.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: fd7a4bed18 ("sched, rt: Convert switched_{from, to}_rt() prio_changed_rt() to balance callbacks")
Link: http://lkml.kernel.org/r/20170124144006.29821-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While in the process of initialising a root domain, if function
cpupri_init() fails the memory allocated in cpudl_init() is not
reclaimed.
Adding a new goto target to cleanup the previous initialistion of
the root_domain's dl_bw structure reclaims said memory.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1485292295-21298-2-git-send-email-mathieu.poirier@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If function cpudl_init() fails the memory allocated for &rd->rto_mask
needs to be freed, something this patch is addressing.
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1485292295-21298-1-git-send-email-mathieu.poirier@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
__migrate_task() can return with a different runqueue locked than the
one we passed as an argument. So that we can repin the lock in
migrate_tasks() (and keep the update_rq_clock() bit) we need to
restore the old rq_flags before repinning.
Note that it wouldn't be correct to change move_queued_task() to repin
because of the change of runqueue and the fact that having an
up-to-date clock on the initial rq doesn't mean the new rq has one
too.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Steve noticed that when we switch from IDLE to SCHED_OTHER we fail to
take the shortcut, even though all runnable tasks are of the fair
class, because prev->sched_class != &fair_sched_class.
Since I reworked the put_prev_task() stuff, we don't really care about
prev->class here, so removing that condition will allow this case.
This increases the likely case from 78% to 98% correct for Steve's
workload.
Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170119174408.GN6485@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When CONFIG_POSIX_TIMERS is disabled, it is preferable to remove related
structures from struct task_struct and struct signal_struct as they
won't contain anything useful and shouldn't be relied upon by mistake.
Code still referencing those structures is also disabled here.
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Mike reported that he could trigger the WARN_ON_ONCE() in
set_sched_clock_stable() using hotplug.
This exposed a fundamental problem with the interface, we should never
mark the TSC stable if we ever find it to be unstable. Therefore
set_sched_clock_stable() is a broken interface.
The reason it existed is that not having it is a pain, it means all
relevant architecture code needs to call clear_sched_clock_stable()
where appropriate.
Of the three architectures that select HAVE_UNSTABLE_SCHED_CLOCK ia64
and parisc are trivial in that they never called
set_sched_clock_stable(), so add an unconditional call to
clear_sched_clock_stable() to them.
For x86 the story is a lot more involved, and what this patch tries to
do is ensure we preserve the status quo. So even is Cyrix or Transmeta
have usable TSC they never called set_sched_clock_stable() so they now
get an explicit mark unstable.
Reported-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9881b024b7 ("sched/clock: Delay switching sched_clock to stable")
Link: http://lkml.kernel.org/r/20170119133633.GB6536@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that IO schedule accounting is done inside __schedule(),
io_schedule() can be split into three steps - prep, schedule, and
finish - where the schedule part doesn't need any special annotation.
This allows marking a sleep as iowait by simply wrapping an existing
blocking function with io_schedule_prepare() and io_schedule_finish().
Because task_struct->in_iowait is single bit, the caller of
io_schedule_prepare() needs to record and the pass its state to
io_schedule_finish() to be safe regarding nesting. While this isn't
the prettiest, these functions are mostly gonna be used by core
functions and we don't want to use more space for ->in_iowait.
While at it, as it's simple to do now, reimplement io_schedule()
without unnecessarily going through io_schedule_timeout().
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adilger.kernel@dilger.ca
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/1477673892-28940-3-git-send-email-tj@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For an interface to support blocking for IOs, it must call
io_schedule() instead of schedule(). This makes it tedious to add IO
blocking to existing interfaces as the switching between schedule()
and io_schedule() is often buried deep.
As we already have a way to mark the task as IO scheduling, this can
be made easier by separating out io_schedule() into multiple steps so
that IO schedule preparation can be performed before invoking a
blocking interface and the actual accounting happens inside the
scheduler.
io_schedule_timeout() does the following three things prior to calling
schedule_timeout().
1. Mark the task as scheduling for IO.
2. Flush out plugged IOs.
3. Account the IO scheduling.
done close to the actual scheduling. This patch moves #3 into the
scheduler so that later patches can separate out preparation and
finish steps from io_schedule().
Patch-originally-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adilger.kernel@dilger.ca
Cc: akpm@linux-foundation.org
Cc: axboe@kernel.dk
Cc: jack@suse.com
Cc: kernel-team@fb.com
Cc: mingbo@fb.com
Cc: tytso@mit.edu
Link: http://lkml.kernel.org/r/20161207204841.GA22296@htj.duckdns.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The update of the share of a cfs_rq is done when its load_avg is updated
but before the group_entity's load_avg has been updated for the past time
slot. This generates wrong load_avg accounting which can be significant
when small tasks are involved in the scheduling.
Let take the example of a task a that is dequeued of its task group A:
root
(cfs_rq)
\
(se)
A
(cfs_rq)
\
(se)
a
Task "a" was the only task in task group A which becomes idle when a is
dequeued.
We have the sequence:
- dequeue_entity a->se
- update_load_avg(a->se)
- dequeue_entity_load_avg(A->cfs_rq, a->se)
- update_cfs_shares(A->cfs_rq)
A->cfs_rq->load.weight == 0
A->se->load.weight is updated with the new share (0 in this case)
- dequeue_entity A->se
- update_load_avg(A->se) but its weight is now null so the last time
slot (up to a tick) will be accounted with a weight of 0 instead of
its real weight during the time slot. The last time slot will be
accounted as an idle one whereas it was a running one.
If the running time of task a is short enough that no tick happens when it
runs, all running time of group entity A->se will be accounted as idle
time.
Instead, we should update the share of a cfs_rq (in fact the weight of its
group entity) only after having updated the load_avg of the group_entity.
update_cfs_shares() now takes the sched_entity as a parameter instead of the
cfs_rq, and the weight of the group_entity is updated only once its load_avg
has been synced with current time.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pjt@google.com
Link: http://lkml.kernel.org/r/1482335426-7664-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Documentation/scheduler/completion.txt says this about complete_all():
"calls complete_all() to signal all current and future waiters."
Which doesn't strictly match the current semantics. Currently
complete_all() is equivalent to UINT_MAX/2 complete() invocations,
which is distinctly less than 'all current and future waiters'
(enumerable vs innumerable), although it has worked in practice.
However, Dmitry had a weird case where it might matter, so change
completions to use saturation semantics for complete()/complete_all().
Once done hits UINT_MAX (and complete_all() sets it there) it will
never again be decremented.
Requested-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: der.herr@hofr.at
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch allows for reading the current (leftover) runtime and
absolute deadline of a SCHED_DEADLINE task through /proc/*/sched
(entries dl.runtime and dl.deadline), while debugging/testing.
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Acked-by: Daniel Bistrot de Oliveira <danielbristot@gmail.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1477473437-10346-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When switching between the unstable and stable variants it is
currently possible that clock discontinuities occur.
And while these will mostly be 'small', attempt to do better.
As observed on my IVB-EP, the sched_clock() is ~1.5s ahead of the
ktime_get_ns() based timeline at the point of switchover
(sched_clock_init_late()) after SMP bringup.
Equally, when the TSC is later found to be unstable -- typically
because SMM tries to hide its SMI latencies by mucking with the TSC --
we want to avoid large jumps.
Since the clocksource watchdog reports the issue after the fact we
cannot exactly fix up time, but since SMI latencies are typically
small (~10ns range), the discontinuity is mainly due to drift between
sched_clock() and ktime_get_ns() (which on my desktop is ~79s over
24days).
I dislike this patch because it adds overhead to the good case in
favour of dealing with badness. But given the widespread failure of
TSC stability this is worth it.
Note that in case the TSC makes drastic jumps after SMP bringup we're
still hosed. There's just not much we can do in that case without
stupid overhead.
If we were to somehow expose tsc_clocksource_reliable (which is hard
because this code is also used on ia64 and parisc) we could avoid some
of the newly introduced overhead.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently we switch to the stable sched_clock if we guess the TSC is
usable, and then switch back to the unstable path if it turns out TSC
isn't stable during SMP bringup after all.
Delay switching to the stable path until after SMP bringup is
complete. This way we'll avoid switching during the time we detect the
worst of the TSC offences.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
sched_clock was still using the deprecated static_key interface.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There's no diagnostic checks for figuring out when we've accidentally
missed update_rq_clock() calls. Let's add some by piggybacking on the
rq_*pin_lock() wrappers.
The idea behind the diagnostic checks is that upon pining rq lock the
rq clock should be updated, via update_rq_clock(), before anybody
reads the clock with rq_clock() or rq_clock_task().
The exception to this rule is when updates have explicitly been
disabled with the rq_clock_skip_update() optimisation.
There are some functions that only unpin the rq lock in order to grab
some other lock and avoid deadlock. In that case we don't need to
update the clock again and the previous diagnostic state can be
carried over in rq_repin_lock() by saving the state in the rq_flags
context.
Since this patch adds a new clock update flag and some already exist
in rq::clock_skip_update, that field has now been renamed. An attempt
has been made to keep the flag manipulation code small and fast since
it's used in the heart of the __schedule() fast path.
For the !CONFIG_SCHED_DEBUG case the only object code change (other
than addresses) is the following change to reset RQCF_ACT_SKIP inside
of __schedule(),
- c7 83 38 09 00 00 00 movl $0x0,0x938(%rbx)
- 00 00 00
+ 83 a3 38 09 00 00 fc andl $0xfffffffc,0x938(%rbx)
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-8-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add the update_rq_clock() call at the top of the callstack instead of
at the bottom where we find it missing, this to aid later effort to
minimize the number of update_rq_lock() calls.
WARNING: CPU: 30 PID: 194 at ../kernel/sched/sched.h:797 assert_clock_updated()
rq->clock_update_flags < RQCF_ACT_SKIP
Call Trace:
dump_stack()
__warn()
warn_slowpath_fmt()
assert_clock_updated.isra.63.part.64()
can_migrate_task()
load_balance()
pick_next_task_fair()
__schedule()
schedule()
worker_thread()
kthread()
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Instead of adding the update_rq_clock() all the way at the bottom of
the callstack, add one at the top, this to aid later effort to
minimize update_rq_lock() calls.
WARNING: CPU: 0 PID: 1 at ../kernel/sched/sched.h:797 detach_task_cfs_rq()
rq->clock_update_flags < RQCF_ACT_SKIP
Call Trace:
dump_stack()
__warn()
warn_slowpath_fmt()
detach_task_cfs_rq()
switched_from_fair()
__sched_setscheduler()
_sched_setscheduler()
sched_set_stop_task()
cpu_stop_create()
__smpboot_create_thread.part.2()
smpboot_register_percpu_thread_cpumask()
cpu_stop_init()
do_one_initcall()
? print_cpu_info()
kernel_init_freeable()
? rest_init()
kernel_init()
ret_from_fork()
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Future patches will emit warnings if rq_clock() is called before
update_rq_clock() inside a rq_pin_lock()/rq_unpin_lock() pair.
Since there is only one caller of idle_balance() we can push the
unpin/repin there.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-7-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
rq_clock() is called from sched_info_{depart,arrive}() after resetting
RQCF_ACT_SKIP but prior to a call to update_rq_clock().
In preparation for pending patches that check whether the rq clock has
been updated inside of a pin context before rq_clock() is called, move
the reset of rq->clock_skip_update immediately before unpinning the rq
lock.
This will avoid the new warnings which check if update_rq_clock() is
being actively skipped.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-6-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In preparation for adding diagnostic checks to catch missing calls to
update_rq_clock(), provide wrappers for (re)pinning and unpinning
rq->lock.
Because the pending diagnostic checks allow state to be maintained in
rq_flags across pin contexts, swap the 'struct pin_cookie' arguments
for 'struct rq_flags *'.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/20160921133813.31976-5-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y used to accumulate user time and
account it on ticks and context switches only through the
vtime_account_user() function.
Now this model has been generalized on the 3 archs for all kind of
cputime (system, irq, ...) and all the cputime flushing happens under
vtime_account_user().
So let's rename this function to better reflect its new role.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1483636310-6557-11-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y to delay
cputime accounting to the tick, let's allow archs to account cputime
directly to gtime.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1483636310-6557-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to prepare for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE=y to delay
cputime accounting to the tick, let's provide APIs to account system
time to precise contexts: hardirq, softirq, pure system, ...
Inspired-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1483636310-6557-4-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
ktime_set(S,N) was required for the timespec storage type and is still
useful for situations where a Seconds and Nanoseconds part of a time value
needs to be converted. For anything where the Seconds argument is 0, this
is pointless and can be replaced with a simple assignment.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
- New cpufreq driver for Broadcom STB SoCs and a Device Tree binding
for it (Markus Mayer).
- Support for ARM Integrator/AP and Integrator/CP in the generic
DT cpufreq driver and elimination of the old Integrator cpufreq
driver (Linus Walleij).
- Support for the zx296718, r8a7743 and r8a7745, Socionext UniPhier,
and PXA SoCs in the the generic DT cpufreq driver (Baoyou Xie,
Geert Uytterhoeven, Masahiro Yamada, Robert Jarzmik).
- cpufreq core fix to eliminate races that may lead to using
inactive policy objects and related cleanups (Rafael Wysocki).
- cpufreq schedutil governor update to make it use SCHED_FIFO
kernel threads (instead of regular workqueues) for doing delayed
work (to reduce the response latency in some cases) and related
cleanups (Viresh Kumar).
- New cpufreq sysfs attribute for resetting statistics (Markus
Mayer).
- cpufreq governors fixes and cleanups (Chen Yu, Stratos Karafotis,
Viresh Kumar).
- Support for using generic cpufreq governors in the intel_pstate
driver (Rafael Wysocki).
- Support for per-logical-CPU P-state limits and the EPP/EPB
(Energy Performance Preference/Energy Performance Bias) knobs
in the intel_pstate driver (Srinivas Pandruvada).
- New CPU ID for Knights Mill in intel_pstate (Piotr Luc).
- intel_pstate driver modification to use the P-state selection
algorithm based on CPU load on platforms with the system profile
in the ACPI tables set to "mobile" (Srinivas Pandruvada).
- intel_pstate driver cleanups (Arnd Bergmann, Rafael Wysocki,
Srinivas Pandruvada).
- cpufreq powernv driver updates including fast switching support
(for the schedutil governor), fixes and cleanus (Akshay Adiga,
Andrew Donnellan, Denis Kirjanov).
- acpi-cpufreq driver rework to switch it over to the new CPU
offline/online state machine (Sebastian Andrzej Siewior).
- Assorted cleanups in cpufreq drivers (Wei Yongjun, Prashanth
Prakash).
- Idle injection rework (to make it use the regular idle path
instead of a home-grown custom one) and related powerclamp
thermal driver updates (Peter Zijlstra, Jacob Pan, Petr Mladek,
Sebastian Andrzej Siewior).
- New CPU IDs for Atom Z34xx and Knights Mill in intel_idle (Andy
Shevchenko, Piotr Luc).
- intel_idle driver cleanups and switch over to using the new CPU
offline/online state machine (Anna-Maria Gleixner, Sebastian
Andrzej Siewior).
- cpuidle DT driver update to support suspend-to-idle properly
(Sudeep Holla).
- cpuidle core cleanups and misc updates (Daniel Lezcano, Pan Bian,
Rafael Wysocki).
- Preliminary support for power domains including CPUs in the
generic power domains (genpd) framework and related DT bindings
(Lina Iyer).
- Assorted fixes and cleanups in the generic power domains (genpd)
framework (Colin Ian King, Dan Carpenter, Geert Uytterhoeven).
- Preliminary support for devices with multiple voltage regulators
and related fixes and cleanups in the Operating Performance Points
(OPP) library (Viresh Kumar, Masahiro Yamada, Stephen Boyd).
- System sleep state selection interface rework to make it easier
to support suspend-to-idle as the default system suspend method
(Rafael Wysocki).
- PM core fixes and cleanups, mostly related to the interactions
between the system suspend and runtime PM frameworks (Ulf Hansson,
Sahitya Tummala, Tony Lindgren).
- Latency tolerance PM QoS framework imorovements (Andrew
Lutomirski).
- New Knights Mill CPU ID for the Intel RAPL power capping driver
(Piotr Luc).
- Intel RAPL power capping driver fixes, cleanups and switch over
to using the new CPU offline/online state machine (Jacob Pan,
Thomas Gleixner, Sebastian Andrzej Siewior).
- Fixes and cleanups in the exynos-ppmu, exynos-nocp, rk3399_dmc,
rockchip-dfi devfreq drivers and the devfreq core (Axel Lin,
Chanwoo Choi, Javier Martinez Canillas, MyungJoo Ham, Viresh
Kumar).
- Fix for false-positive KASAN warnings during resume from ACPI S3
(suspend-to-RAM) on x86 (Josh Poimboeuf).
- Memory map verification during resume from hibernation on x86 to
ensure a consistent address space layout (Chen Yu).
- Wakeup sources debugging enhancement (Xing Wei).
- rockchip-io AVS driver cleanup (Shawn Lin).
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Merge tag 'pm-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"Again, cpufreq gets more changes than the other parts this time (one
new driver, one old driver less, a bunch of enhancements of the
existing code, new CPU IDs, fixes, cleanups)
There also are some changes in cpuidle (idle injection rework, a
couple of new CPU IDs, online/offline rework in intel_idle, fixes and
cleanups), in the generic power domains framework (mostly related to
supporting power domains containing CPUs), and in the Operating
Performance Points (OPP) library (mostly related to supporting devices
with multiple voltage regulators)
In addition to that, the system sleep state selection interface is
modified to make it easier for distributions with unchanged user space
to support suspend-to-idle as the default system suspend method, some
issues are fixed in the PM core, the latency tolerance PM QoS
framework is improved a bit, the Intel RAPL power capping driver is
cleaned up and there are some fixes and cleanups in the devfreq
subsystem
Specifics:
- New cpufreq driver for Broadcom STB SoCs and a Device Tree binding
for it (Markus Mayer)
- Support for ARM Integrator/AP and Integrator/CP in the generic DT
cpufreq driver and elimination of the old Integrator cpufreq driver
(Linus Walleij)
- Support for the zx296718, r8a7743 and r8a7745, Socionext UniPhier,
and PXA SoCs in the the generic DT cpufreq driver (Baoyou Xie,
Geert Uytterhoeven, Masahiro Yamada, Robert Jarzmik)
- cpufreq core fix to eliminate races that may lead to using inactive
policy objects and related cleanups (Rafael Wysocki)
- cpufreq schedutil governor update to make it use SCHED_FIFO kernel
threads (instead of regular workqueues) for doing delayed work (to
reduce the response latency in some cases) and related cleanups
(Viresh Kumar)
- New cpufreq sysfs attribute for resetting statistics (Markus Mayer)
- cpufreq governors fixes and cleanups (Chen Yu, Stratos Karafotis,
Viresh Kumar)
- Support for using generic cpufreq governors in the intel_pstate
driver (Rafael Wysocki)
- Support for per-logical-CPU P-state limits and the EPP/EPB (Energy
Performance Preference/Energy Performance Bias) knobs in the
intel_pstate driver (Srinivas Pandruvada)
- New CPU ID for Knights Mill in intel_pstate (Piotr Luc)
- intel_pstate driver modification to use the P-state selection
algorithm based on CPU load on platforms with the system profile in
the ACPI tables set to "mobile" (Srinivas Pandruvada)
- intel_pstate driver cleanups (Arnd Bergmann, Rafael Wysocki,
Srinivas Pandruvada)
- cpufreq powernv driver updates including fast switching support
(for the schedutil governor), fixes and cleanus (Akshay Adiga,
Andrew Donnellan, Denis Kirjanov)
- acpi-cpufreq driver rework to switch it over to the new CPU
offline/online state machine (Sebastian Andrzej Siewior)
- Assorted cleanups in cpufreq drivers (Wei Yongjun, Prashanth
Prakash)
- Idle injection rework (to make it use the regular idle path instead
of a home-grown custom one) and related powerclamp thermal driver
updates (Peter Zijlstra, Jacob Pan, Petr Mladek, Sebastian Andrzej
Siewior)
- New CPU IDs for Atom Z34xx and Knights Mill in intel_idle (Andy
Shevchenko, Piotr Luc)
- intel_idle driver cleanups and switch over to using the new CPU
offline/online state machine (Anna-Maria Gleixner, Sebastian
Andrzej Siewior)
- cpuidle DT driver update to support suspend-to-idle properly
(Sudeep Holla)
- cpuidle core cleanups and misc updates (Daniel Lezcano, Pan Bian,
Rafael Wysocki)
- Preliminary support for power domains including CPUs in the generic
power domains (genpd) framework and related DT bindings (Lina Iyer)
- Assorted fixes and cleanups in the generic power domains (genpd)
framework (Colin Ian King, Dan Carpenter, Geert Uytterhoeven)
- Preliminary support for devices with multiple voltage regulators
and related fixes and cleanups in the Operating Performance Points
(OPP) library (Viresh Kumar, Masahiro Yamada, Stephen Boyd)
- System sleep state selection interface rework to make it easier to
support suspend-to-idle as the default system suspend method
(Rafael Wysocki)
- PM core fixes and cleanups, mostly related to the interactions
between the system suspend and runtime PM frameworks (Ulf Hansson,
Sahitya Tummala, Tony Lindgren)
- Latency tolerance PM QoS framework imorovements (Andrew Lutomirski)
- New Knights Mill CPU ID for the Intel RAPL power capping driver
(Piotr Luc)
- Intel RAPL power capping driver fixes, cleanups and switch over to
using the new CPU offline/online state machine (Jacob Pan, Thomas
Gleixner, Sebastian Andrzej Siewior)
- Fixes and cleanups in the exynos-ppmu, exynos-nocp, rk3399_dmc,
rockchip-dfi devfreq drivers and the devfreq core (Axel Lin,
Chanwoo Choi, Javier Martinez Canillas, MyungJoo Ham, Viresh Kumar)
- Fix for false-positive KASAN warnings during resume from ACPI S3
(suspend-to-RAM) on x86 (Josh Poimboeuf)
- Memory map verification during resume from hibernation on x86 to
ensure a consistent address space layout (Chen Yu)
- Wakeup sources debugging enhancement (Xing Wei)
- rockchip-io AVS driver cleanup (Shawn Lin)"
* tag 'pm-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (127 commits)
devfreq: rk3399_dmc: Don't use OPP structures outside of RCU locks
devfreq: rk3399_dmc: Remove dangling rcu_read_unlock()
devfreq: exynos: Don't use OPP structures outside of RCU locks
Documentation: intel_pstate: Document HWP energy/performance hints
cpufreq: intel_pstate: Support for energy performance hints with HWP
cpufreq: intel_pstate: Add locking around HWP requests
PM / sleep: Print active wakeup sources when blocking on wakeup_count reads
PM / core: Fix bug in the error handling of async suspend
PM / wakeirq: Fix dedicated wakeirq for drivers not using autosuspend
PM / Domains: Fix compatible for domain idle state
PM / OPP: Don't WARN on multiple calls to dev_pm_opp_set_regulators()
PM / OPP: Allow platform specific custom set_opp() callbacks
PM / OPP: Separate out _generic_set_opp()
PM / OPP: Add infrastructure to manage multiple regulators
PM / OPP: Pass struct dev_pm_opp_supply to _set_opp_voltage()
PM / OPP: Manage supply's voltage/current in a separate structure
PM / OPP: Don't use OPP structure outside of rcu protected section
PM / OPP: Reword binding supporting multiple regulators per device
PM / OPP: Fix incorrect cpu-supply property in binding
cpuidle: Add a kerneldoc comment to cpuidle_use_deepest_state()
..
Pull scheduler updates from Ingo Molnar:
"The main scheduler changes in this cycle were:
- support Intel Turbo Boost Max Technology 3.0 (TBM3) by introducig a
notion of 'better cores', which the scheduler will prefer to
schedule single threaded workloads on. (Tim Chen, Srinivas
Pandruvada)
- enhance the handling of asymmetric capacity CPUs further (Morten
Rasmussen)
- improve/fix load handling when moving tasks between task groups
(Vincent Guittot)
- simplify and clean up the cputime code (Stanislaw Gruszka)
- improve mass fork()ed task spread a.k.a. hackbench speedup (Vincent
Guittot)
- make struct kthread kmalloc()ed and related fixes (Oleg Nesterov)
- add uaccess atomicity debugging (when using access_ok() in the
wrong context), under CONFIG_DEBUG_ATOMIC_SLEEP=y (Peter Zijlstra)
- implement various fixes, cleanups and other enhancements (Daniel
Bristot de Oliveira, Martin Schwidefsky, Rafael J. Wysocki)"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (41 commits)
sched/core: Use load_avg for selecting idlest group
sched/core: Fix find_idlest_group() for fork
kthread: Don't abuse kthread_create_on_cpu() in __kthread_create_worker()
kthread: Don't use to_live_kthread() in kthread_[un]park()
kthread: Don't use to_live_kthread() in kthread_stop()
Revert "kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function"
kthread: Make struct kthread kmalloc'ed
x86/uaccess, sched/preempt: Verify access_ok() context
sched/x86: Make CONFIG_SCHED_MC_PRIO=y easier to enable
sched/x86: Change CONFIG_SCHED_ITMT to CONFIG_SCHED_MC_PRIO
x86/sched: Use #include <linux/mutex.h> instead of #include <asm/mutex.h>
cpufreq/intel_pstate: Use CPPC to get max performance
acpi/bus: Set _OSC for diverse core support
acpi/bus: Enable HWP CPPC objects
x86/sched: Add SD_ASYM_PACKING flags to x86 ITMT CPU
x86/sysctl: Add sysctl for ITMT scheduling feature
x86: Enable Intel Turbo Boost Max Technology 3.0
x86/topology: Define x86's arch_update_cpu_topology
sched: Extend scheduler's asym packing
sched/fair: Clean up the tunable parameter definitions
...
* pm-cpuidle:
cpuidle: Add a kerneldoc comment to cpuidle_use_deepest_state()
cpuidle: fix improper return value on error
intel_idle: Convert to hotplug state machine
intel_idle: Remove superfluous SMP fuction call
MAINTAINERS: Add Jacob Pan as a new intel_idle maintainer
MAINTAINERS: Add bug tracking system location entries for cpuidle
x86/intel_idle: Add Knights Mill CPUID
x86/intel_idle: Add CPU model 0x4a (Atom Z34xx series)
thermal/intel_powerclamp: stop sched tick in forced idle
thermal/intel_powerclamp: Convert to CPU hotplug state
thermal/intel_powerclamp: Convert the kthread to kthread worker API
thermal/intel_powerclamp: Remove duplicated code that starts the kthread
sched/idle: Add support for tasks that inject idle
cpuidle: Allow enforcing deepest idle state selection
cpuidle/powernv: staticise powernv_idle_driver
cpuidle: dt: assign ->enter_freeze to same as ->enter callback function
cpuidle: governors: Remove remaining old module code
* pm-cpufreq: (51 commits)
Documentation: intel_pstate: Document HWP energy/performance hints
cpufreq: intel_pstate: Support for energy performance hints with HWP
cpufreq: intel_pstate: Add locking around HWP requests
cpufreq: ondemand: Set MIN_FREQUENCY_UP_THRESHOLD to 1
cpufreq: intel_pstate: Add Knights Mill CPUID
MAINTAINERS: Add bug tracking system location entry for cpufreq
cpufreq: dt: Add support for zx296718
cpufreq: acpi-cpufreq: drop rdmsr_on_cpus() usage
cpufreq: acpi-cpufreq: Convert to hotplug state machine
cpufreq: intel_pstate: fix intel_pstate_exit_perf_limits() prototype
cpufreq: intel_pstate: Set EPP/EPB to 0 in performance mode
cpufreq: schedutil: Rectify comment in sugov_irq_work() function
cpufreq: intel_pstate: increase precision of performance limits
cpufreq: intel_pstate: round up min_perf limits
cpufreq: Make cpufreq_update_policy() void
ACPI / processor: Make acpi_processor_ppc_has_changed() void
cpufreq: Avoid using inactive policies
cpufreq: intel_pstate: Generic governors support
cpufreq: intel_pstate: Request P-states control from SMM if needed
cpufreq: dt: Add support for r8a7743 and r8a7745
...
find_idlest_group() only compares the runnable_load_avg when looking
for the least loaded group. But on fork intensive use case like
hackbench where tasks blocked quickly after the fork, this can lead to
selecting the same CPU instead of other CPUs, which have similar
runnable load but a lower load_avg.
When the runnable_load_avg of 2 CPUs are close, we now take into
account the amount of blocked load as a 2nd selection factor. There is
now 3 zones for the runnable_load of the rq:
- [0 .. (runnable_load - imbalance)]:
Select the new rq which has significantly less runnable_load
- [(runnable_load - imbalance) .. (runnable_load + imbalance)]:
The runnable loads are close so we use load_avg to chose
between the 2 rq
- [(runnable_load + imbalance) .. ULONG_MAX]:
Keep the current rq which has significantly less runnable_load
The scale factor that is currently used for comparing runnable_load,
doesn't work well with small value. As an example, the use of a
scaling factor fails as soon as this_runnable_load == 0 because we
always select local rq even if min_runnable_load is only 1, which
doesn't really make sense because they are just the same. So instead
of scaling factor, we use an absolute margin for runnable_load to
detect CPUs with similar runnable_load and we keep using scaling
factor for blocked load.
For use case like hackbench, this enable the scheduler to select
different CPUs during the fork sequence and to spread tasks across the
system.
Tests have been done on a Hikey board (ARM based octo cores) for
several kernel. The result below gives min, max, avg and stdev values
of 18 runs with each configuration.
The patches depend on the "no missing update_rq_clock()" work.
hackbench -P -g 1
ea86cb4b767dc603c902 v4.8 v4.8+patches
min 0.049 0.050 0.051 0,048
avg 0.057 0.057(0%) 0.057(0%) 0,055(+5%)
max 0.066 0.068 0.070 0,063
stdev +/-9% +/-9% +/-8% +/-9%
More performance numbers here:
https://lkml.kernel.org/r/20161203214707.GI20785@codeblueprint.co.uk
Tested-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: kernellwp@gmail.com
Cc: umgwanakikbuti@gmail.com
Cc: yuyang.du@intel.comc
Link: http://lkml.kernel.org/r/1481216215-24651-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
During fork, the utilization of a task is init once the rq has been
selected because the current utilization level of the rq is used to
set the utilization of the fork task. As the task's utilization is
still 0 at this step of the fork sequence, it doesn't make sense to
look for some spare capacity that can fit the task's utilization.
Furthermore, I can see perf regressions for the test:
hackbench -P -g 1
because the least loaded policy is always bypassed and tasks are not
spread during fork.
With this patch and the fix below, we are back to same performances as
for v4.8. The fix below is only a temporary one used for the test
until a smarter solution is found because we can't simply remove the
test which is useful for others benchmarks
| @@ -5708,13 +5708,6 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
|
| avg_cost = this_sd->avg_scan_cost;
|
| - /*
| - * Due to large variance we need a large fuzz factor; hackbench in
| - * particularly is sensitive here.
| - */
| - if ((avg_idle / 512) < avg_cost)
| - return -1;
| -
| time = local_clock();
|
| for_each_cpu_wrap(cpu, sched_domain_span(sd), target, wrap) {
Tested-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: kernellwp@gmail.com
Cc: umgwanakikbuti@gmail.com
Cc: yuyang.du@intel.comc
Link: http://lkml.kernel.org/r/1481216215-24651-2-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Idle injection drivers such as Intel powerclamp and ACPI PAD drivers use
realtime tasks to take control of CPU then inject idle. There are two
issues with this approach:
1. Low efficiency: injected idle task is treated as busy so sched ticks
do not stop during injected idle period, the result of these
unwanted wakeups can be ~20% loss in power savings.
2. Idle accounting: injected idle time is presented to user as busy.
This patch addresses the issues by introducing a new PF_IDLE flag which
allows any given task to be treated as idle task while the flag is set.
Therefore, idle injection tasks can run through the normal flow of NOHZ
idle enter/exit to get the correct accounting as well as tick stop when
possible.
The implication is that idle task is then no longer limited to PID == 0.
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When idle injection is used to cap power, we need to override the
governor's choice of idle states.
For this reason, make it possible the deepest idle state selection to
be enforced by setting a flag on a given CPU to achieve the maximum
potential power draw reduction.
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
[ rjw: Subject & changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This patch rectifies a comment present in sugov_irq_work() function to
follow proper grammar.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
We generalize the scheduler's asym packing to provide an ordering
of the cpu beyond just the cpu number. This allows the use of the
ASYM_PACKING scheduler machinery to move loads to preferred CPU in a
sched domain. The preference is defined with the cpu priority
given by arch_asym_cpu_priority(cpu).
We also record the most preferred cpu in a sched group when
we build the cpu's capacity for fast lookup of preferred cpu
during load balancing.
Co-developed-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-pm@vger.kernel.org
Cc: jolsa@redhat.com
Cc: rjw@rjwysocki.net
Cc: linux-acpi@vger.kernel.org
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: bp@suse.de
Link: http://lkml.kernel.org/r/0e73ae12737dfaafa46c07066cc7c5d3f1675e46.1479844244.git.tim.c.chen@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Michael Kerrisk reported:
> Regarding the previous paragraph... My tests indicate
> that writing *any* value to the autogroup [nice priority level]
> file causes the task group to get a lower priority.
Because autogroup didn't call the then meaningless scale_load()...
Autogroup nice level adjustment has been broken ever since load
resolution was increased for 64-bit kernels. Use scale_load() to
scale group weight.
Michael Kerrisk tested this patch to fix the problem:
> Applied and tested against 4.9-rc6 on an Intel u7 (4 cores).
> Test setup:
>
> Terminal window 1: running 40 CPU burner jobs
> Terminal window 2: running 40 CPU burner jobs
> Terminal window 1: running 1 CPU burner job
>
> Demonstrated that:
> * Writing "0" to the autogroup file for TW1 now causes no change
> to the rate at which the process on the terminal consume CPU.
> * Writing -20 to the autogroup file for TW1 caused those processes
> to get the lion's share of CPU while TW2 TW3 get a tiny amount.
> * Writing -20 to the autogroup files for TW1 and TW3 allowed the
> process on TW3 to get as much CPU as it was getting as when
> the autogroup nice values for both terminals were 0.
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Tested-by: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-man <linux-man@vger.kernel.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/1479897217.4306.6.camel@gmx.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
No change in functionality:
- align the default values vertically to make them easier to scan
- standardize the 'default:' lines
- fix minor whitespace typos
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Exactly because for_each_thread() in autogroup_move_group() can't see it
and update its ->sched_task_group before _put() and possibly free().
So the exiting task needs another sched_move_task() before exit_notify()
and we need to re-introduce the PF_EXITING (or similar) check removed by
the previous change for another reason.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hartsjc@redhat.com
Cc: vbendel@redhat.com
Cc: vlovejoy@redhat.com
Link: http://lkml.kernel.org/r/20161114184612.GA15968@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The PF_EXITING check in task_wants_autogroup() is no longer needed. Remove
it, but see the next patch.
However the comment is correct in that autogroup_move_group() must always
change task_group() for every thread so the sysctl_ check is very wrong;
we can race with cgroups and even sys_setsid() is not safe because a task
running with task_group() == ag->tg must participate in refcounting:
int main(void)
{
int sctl = open("/proc/sys/kernel/sched_autogroup_enabled", O_WRONLY);
assert(sctl > 0);
if (fork()) {
wait(NULL); // destroy the child's ag/tg
pause();
}
assert(pwrite(sctl, "1\n", 2, 0) == 2);
assert(setsid() > 0);
if (fork())
pause();
kill(getppid(), SIGKILL);
sleep(1);
// The child has gone, the grandchild runs with kref == 1
assert(pwrite(sctl, "0\n", 2, 0) == 2);
assert(setsid() > 0);
// runs with the freed ag/tg
for (;;)
sleep(1);
return 0;
}
crashes the kernel. It doesn't really need sleep(1), it doesn't matter if
autogroup_move_group() actually frees the task_group or this happens later.
Reported-by: Vern Lovejoy <vlovejoy@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: hartsjc@redhat.com
Cc: vbendel@redhat.com
Link: http://lkml.kernel.org/r/20161114184609.GA15965@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Execute the irq-work specific initialization/exit code only when the
fast path isn't available.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
If slow path frequency changes are conducted in a SCHED_OTHER context
then they may be delayed for some amount of time, including
indefinitely, when real time or deadline activity is taking place.
Move the slow path to a real time kernel thread. In the future the
thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set
to 50 for now.
Hackbench results on ARM Exynos, dual core A15 platform for 10
iterations:
$ hackbench -s 100 -l 100 -g 10 -f 20
Before After
---------------------------------
1.808 1.603
1.847 1.251
2.229 1.590
1.952 1.600
1.947 1.257
1.925 1.627
2.694 1.620
1.258 1.621
1.919 1.632
1.250 1.240
Average:
1.8829 1.5041
Based on initial work by Steve Muckle.
Signed-off-by: Steve Muckle <smuckle.linux@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The fast_switch_enabled flag will be used by both sugov_policy_alloc()
and sugov_policy_free() with a later patch.
Prepare for that by moving the calls to enable and disable it to the
beginning of sugov_init() and end of sugov_exit().
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Switch to the more common practice of writing labels.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
A task can be asynchronously detached from cfs_rq when migrating
between CPUs. The load of the migrated task is then removed from
source cfs_rq during its next update. We use this event to set
propagation flag.
During the load balance, we take advantage of the update of blocked
load to propagate any pending changes.
The propagation relies on patch:
"sched: Fix hierarchical order in rq->leaf_cfs_rq_list"
... which orders children and parents, to ensure that it's done in one pass.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-6-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a task moves from/to a cfs_rq, we set a flag which is then used to
propagate the change at parent level (sched_entity and cfs_rq) during
next update. If the cfs_rq is throttled, the flag will stay pending until
the cfs_rq is unthrottled.
For propagating the utilization, we copy the utilization of group cfs_rq to
the sched_entity.
For propagating the load, we have to take into account the load of the
whole task group in order to evaluate the load of the sched_entity.
Similarly to what was done before the rewrite of PELT, we add a correction
factor in case the task group's load is greater than its share so it will
contribute the same load of a task of equal weight.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-5-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Every time we modify load/utilization of sched_entity, we start to
sync it with its cfs_rq. This update is done in different ways:
- when attaching/detaching a sched_entity, we update cfs_rq and then
we sync the entity with the cfs_rq.
- when enqueueing/dequeuing the sched_entity, we update both
sched_entity and cfs_rq metrics to now.
Use update_load_avg() everytime we have to update and sync cfs_rq and
sched_entity before changing the state of a sched_enity.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Fix the insertion of cfs_rq in rq->leaf_cfs_rq_list to ensure that a
child will always be called before its parent.
The hierarchical order in shares update list has been introduced by
commit:
67e86250f8 ("sched: Introduce hierarchal order on shares update list")
With the current implementation a child can be still put after its
parent.
Lets take the example of:
root
\
b
/\
c d*
|
e*
with root -> b -> c already enqueued but not d -> e so the
leaf_cfs_rq_list looks like: head -> c -> b -> root -> tail
The branch d -> e will be added the first time that they are enqueued,
starting with e then d.
When e is added, its parents is not already on the list so e is put at
the tail : head -> c -> b -> root -> e -> tail
Then, d is added at the head because its parent is already on the
list: head -> d -> c -> b -> root -> e -> tail
e is not placed at the right position and will be called the last
whereas it should be called at the beginning.
Because it follows the bottom-up enqueue sequence, we are sure that we
will finished to add either a cfs_rq without parent or a cfs_rq with a
parent that is already on the list. We can use this event to detect
when we have finished to add a new branch. For the others, whose
parents are not already added, we have to ensure that they will be
added after their children that have just been inserted the steps
before, and after any potential parents that are already in the list.
The easiest way is to put the cfs_rq just after the last inserted one
and to keep track of it untl the branch is fully added.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-3-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For asymmetric CPU capacity systems it is counter-productive for
throughput if low capacity CPUs are pulling tasks from non-overloaded
CPUs with higher capacity. The assumption is that higher CPU capacity is
preferred over running alone in a group with lower CPU capacity.
This patch rejects higher CPU capacity groups with one or less task per
CPU as potential busiest group which could otherwise lead to a series of
failing load-balancing attempts leading to a force-migration.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-5-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
struct sched_group_capacity currently represents the compute capacity
sum of all CPUs in the sched_group.
Unless it is divided by the group_weight to get the average capacity
per CPU, it hides differences in CPU capacity for mixed capacity systems
(e.g. high RT/IRQ utilization or ARM big.LITTLE).
But even the average may not be sufficient if the group covers CPUs of
different capacities.
Instead, by extending struct sched_group_capacity to indicate min per-CPU
capacity in the group a suitable group for a given task utilization can
more easily be found such that CPUs with reduced capacity can be avoided
for tasks with high utilization (not implemented by this patch).
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-4-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In low-utilization scenarios comparing relative loads in
find_idlest_group() doesn't always lead to the most optimum choice.
Systems with groups containing different numbers of cpus and/or cpus of
different compute capacity are significantly better off when considering
spare capacity rather than relative load in those scenarios.
In addition to existing load based search an alternative spare capacity
based candidate sched_group is found and selected instead if sufficient
spare capacity exists. If not, existing behaviour is preserved.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-3-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
At task wake-up load-tracking isn't updated until the task is enqueued.
The task's own view of its utilization contribution may therefore not be
aligned with its contribution to the cfs_rq load-tracking which may have
been updated in the meantime. Basically, the task's own utilization
hasn't yet accounted for the sleep decay, while the cfs_rq may have
(partially). Estimating the cfs_rq utilization in case the task is
migrated at wake-up as task_rq(p)->cfs.avg.util_avg - p->se.avg.util_avg
is therefore incorrect as the two load-tracking signals aren't time
synchronized (different last update).
To solve this problem, this patch synchronizes the task utilization with
its previous rq before the task utilization is used in the wake-up path.
Currently the update/synchronization is done _after_ the task has been
placed by select_task_rq_fair(). The synchronization is done without
having to take the rq lock using the existing mechanism used in
remove_entity_load_avg().
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1476452472-24740-2-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
For s390 kernel builds I keep getting this warning:
kernel/sched/cpuacct.c: In function 'cpuacct_stats_show':
kernel/sched/cpuacct.c:298:25: warning: format '%lld' expects argument of type 'long long int', but argument 4 has type 'clock_t {aka long int}' [-Wformat=]
seq_printf(sf, "%s %lld\n",
Silence the warning by adding an explicit cast.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161111142749.6545-1-schwidefsky@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now since fetch_task_cputime() has no other users than task_cputime(),
its code could be used directly in task_cputime().
Moreover since only 2 task_cputime() calls of 17 use a NULL argument,
we can add dummy variables to those calls and remove NULL checks from
task_cputimes().
Also remove NULL checks from task_cputimes_scaled().
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1479175612-14718-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Only s390 and powerpc have hardware facilities allowing to measure
cputimes scaled by frequency. On all other architectures
utimescaled/stimescaled are equal to utime/stime (however they are
accounted separately).
Remove {u,s}timescaled accounting on all architectures except
powerpc and s390, where those values are explicitly accounted
in the proper places.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161031162143.GB12646@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently cputime_to_scaled() just return it's argument on
all implementations, we don't need to call this function.
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Paul Mackerras <paulus@ozlabs.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Neuling <mikey@neuling.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1479175612-14718-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In the comment:
/*
* The task might have changed its scheduling policy to something
* different than SCHED_DEADLINE (through switched_fromd_dl()).
*/
s/fromd/from/
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5408b3b3f9ee197a7b7f10fb834341100a4f2c88.1478599881.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When CONFIG_THREAD_INFO_IN_TASK=y, it is possible that an exited thread
remains in the task list after its stack pointer was already set to NULL.
Therefore, thread_saved_pc() and stack_not_used() in sched_show_task()
will trigger NULL pointer dereference if an attempt to dump such thread's
traces (e.g. SysRq-t, khungtaskd) is made.
Since show_stack() in sched_show_task() calls try_get_task_stack() and
sched_show_task() is called from interrupt context, calling
try_get_task_stack() from sched_show_task() will be safe as well.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: brgerst@gmail.com
Cc: jann@thejh.net
Cc: keescook@chromium.org
Cc: linux-api@vger.kernel.org
Cc: tycho.andersen@canonical.com
Link: http://lkml.kernel.org/r/201611021950.FEJ34368.HFFJOOMLtQOVSF@I-love.SAKURA.ne.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull objtool, irq and scheduler fixes from Ingo Molnar:
"One more objtool fixlet for GCC6 code generation patterns, an irq
DocBook fix and an unused variable warning fix in the scheduler"
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix rare switch jump table pattern detection
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
doc: Add missing parameter for msi_setup
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Remove unused but set variable 'rq'
The per-zone waitqueues exist because of a scalability issue with the
page waitqueues on some NUMA machines, but it turns out that they hurt
normal loads, and now with the vmalloced stacks they also end up
breaking gfs2 that uses a bit_wait on a stack object:
wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE)
where 'gh' can be a reference to the local variable 'mount_gh' on the
stack of fill_super().
The reason the per-zone hash table breaks for this case is that there is
no "zone" for virtual allocations, and trying to look up the physical
page to get at it will fail (with a BUG_ON()).
It turns out that I actually complained to the mm people about the
per-zone hash table for another reason just a month ago: the zone lookup
also hurts the regular use of "unlock_page()" a lot, because the zone
lookup ends up forcing several unnecessary cache misses and generates
horrible code.
As part of that earlier discussion, we had a much better solution for
the NUMA scalability issue - by just making the page lock have a
separate contention bit, the waitqueue doesn't even have to be looked at
for the normal case.
Peter Zijlstra already has a patch for that, but let's see if anybody
even notices. In the meantime, let's fix the actual gfs2 breakage by
simplifying the bitlock waitqueues and removing the per-zone issue.
Reported-by: Andreas Gruenbacher <agruenba@redhat.com>
Tested-by: Bob Peterson <rpeterso@redhat.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit:
8663e24d56 ("sched/fair: Reorder cgroup creation code")
... the variable 'rq' in alloc_fair_sched_group() is set but no longer used.
Remove it to fix the following GCC warning when building with 'W=1':
kernel/sched/fair.c:8842:13: warning: variable ‘rq’ set but not used [-Wunused-but-set-variable]
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161026113704.8981-1-tklauser@distanz.ch
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The current mutex implementation has an atomic lock word and a
non-atomic owner field.
This disparity leads to a number of issues with the current mutex code
as it means that we can have a locked mutex without an explicit owner
(because the owner field has not been set, or already cleared).
This leads to a number of weird corner cases, esp. between the
optimistic spinning and debug code. Where the optimistic spinning
code needs the owner field updated inside the lock region, the debug
code is more relaxed because the whole lock is serialized by the
wait_lock.
Also, the spinning code itself has a few corner cases where we need to
deal with a held lock without an owner field.
Furthermore, it becomes even more of a problem when trying to fix
starvation cases in the current code. We end up stacking special case
on special case.
To solve this rework the basic mutex implementation to be a single
atomic word that contains the owner and uses the low bits for extra
state.
This matches how PI futexes and rt_mutex already work. By having the
owner an integral part of the lock state a lot of the problems
dissapear and we get a better option to deal with starvation cases,
direct owner handoff.
Changing the basic mutex does however invalidate all the arch specific
mutex code; this patch leaves that unused in-place, a later patch will
remove that.
Tested-by: Jason Low <jason.low2@hpe.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There were a few questions wrt. how sleep-wakeup works. Try and explain
it more.
Requested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The last user of this tunable was removed in 2012 in commit:
82958366cf ("sched: Replace update_shares weight distribution with per-entity computation")
Delete it since its very existence confuses people.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161019141059.26408-1-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A scheduler performance regression has been reported by Joseph Salisbury,
which he bisected back to:
3d30544f02 ("sched/fair: Apply more PELT fixes)
The regression triggers when several levels of task groups are involved
(read: SystemD) and cpu_possible_mask != cpu_present_mask.
The root cause is that group entity's load (tg_child->se[i]->avg.load_avg)
is initialized to scale_load_down(se->load.weight). During the creation of
a child task group, its group entities on possible CPUs are attached to
parent's cfs_rq (tg_parent) and their loads are added to the parent's load
(tg_parent->load_avg) with update_tg_load_avg().
But only the load on online CPUs will then be updated to reflect real load,
whereas load on other CPUs will stay at the initial value.
The result is a tg_parent->load_avg that is higher than the real load, the
weight of group entities (tg_parent->se[i]->load.weight) on online CPUs is
smaller than it should be, and the task group gets a less running time than
what it could expect.
( This situation can be detected with /proc/sched_debug. The ".tg_load_avg"
of the task group will be much higher than sum of ".tg_load_avg_contrib"
of online cfs_rqs of the task group. )
The load of group entities don't have to be intialized to something else
than 0 because their load will increase when an entity is attached.
Reported-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org> # 4.8.x
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: joonwoop@codeaurora.org
Fixes: 3d30544f02 ("sched/fair: Apply more PELT fixes)
Link: http://lkml.kernel.org/r/1476881123-10159-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fix from Ingo Molnar:
"Fix a crash that can trigger when racing with CPU hotplug: we didn't
use sched-domains data structures carefully enough in select_idle_cpu()"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix sched domains NULL dereference in select_idle_sibling()
extract as much possible uncertainty from a running system at boot time as
possible, hoping to capitalize on any possible variation in CPU operation
(due to runtime data differences, hardware differences, SMP ordering,
thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example for
how to manipulate kernel code using the gcc plugin internals.
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Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull gcc plugins update from Kees Cook:
"This adds a new gcc plugin named "latent_entropy". It is designed to
extract as much possible uncertainty from a running system at boot
time as possible, hoping to capitalize on any possible variation in
CPU operation (due to runtime data differences, hardware differences,
SMP ordering, thermal timing variation, cache behavior, etc).
At the very least, this plugin is a much more comprehensive example
for how to manipulate kernel code using the gcc plugin internals"
* tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
latent_entropy: Mark functions with __latent_entropy
gcc-plugins: Add latent_entropy plugin
Pull cgroup updates from Tejun Heo:
- tracepoints for basic cgroup management operations added
- kernfs and cgroup path formatting functions updated to behave in the
style of strlcpy()
- non-critical bug fixes
* 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
blkcg: Unlock blkcg_pol_mutex only once when cpd == NULL
cgroup: fix error handling regressions in proc_cgroup_show() and cgroup_release_agent()
cpuset: fix error handling regression in proc_cpuset_show()
cgroup: add tracepoints for basic operations
cgroup: make cgroup_path() and friends behave in the style of strlcpy()
kernfs: remove kernfs_path_len()
kernfs: make kernfs_path*() behave in the style of strlcpy()
kernfs: add dummy implementation of kernfs_path_from_node()
Commit:
10e2f1acd0 ("sched/core: Rewrite and improve select_idle_siblings()")
... improved select_idle_sibling(), but also triggered a regression (crash)
during CPU-hotplug:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000078
IP: [<ffffffffb10cd332>] select_idle_sibling+0x1c2/0x4f0
Call Trace:
<IRQ>
select_task_rq_fair+0x749/0x930
? select_task_rq_fair+0xb4/0x930
? __lock_is_held+0x54/0x70
try_to_wake_up+0x19a/0x5b0
default_wake_function+0x12/0x20
autoremove_wake_function+0x12/0x40
__wake_up_common+0x55/0x90
__wake_up+0x39/0x50
wake_up_klogd_work_func+0x40/0x60
irq_work_run_list+0x57/0x80
irq_work_run+0x2c/0x30
smp_irq_work_interrupt+0x2e/0x40
irq_work_interrupt+0x96/0xa0
<EOI>
? _raw_spin_unlock_irqrestore+0x45/0x80
try_to_wake_up+0x4a/0x5b0
wake_up_state+0x10/0x20
__kthread_unpark+0x67/0x70
kthread_unpark+0x22/0x30
cpuhp_online_idle+0x3e/0x70
cpu_startup_entry+0x6a/0x450
start_secondary+0x154/0x180
This can be reproduced by running the ftrace test case of kselftest, the
test case will hot-unplug the CPU and the CPU will attach to the NULL
sched-domain during scheduler teardown.
The step 2 for the rewrite select_idle_siblings():
| Step 2) tracks the average cost of the scan and compares this to the
| average idle time guestimate for the CPU doing the wakeup.
If the CPU which doing the wakeup is the going hot-unplug CPU, then NULL
sched domain will be dereferenced to acquire the average cost of the scan.
This patch fix it by failing the search of an idle CPU in the LLC process
if this sched domain is NULL.
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1475971443-3187-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The __latent_entropy gcc attribute can be used only on functions and
variables. If it is on a function then the plugin will instrument it for
gathering control-flow entropy. If the attribute is on a variable then
the plugin will initialize it with random contents. The variable must
be an integer, an integer array type or a structure with integer fields.
These specific functions have been selected because they are init
functions (to help gather boot-time entropy), are called at unpredictable
times, or they have variable loops, each of which provide some level of
latent entropy.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
[kees: expanded commit message]
Signed-off-by: Kees Cook <keescook@chromium.org>
When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative. Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".
We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.
This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.
Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.com
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm]
Tested-by: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull low-level x86 updates from Ingo Molnar:
"In this cycle this topic tree has become one of those 'super topics'
that accumulated a lot of changes:
- Add CONFIG_VMAP_STACK=y support to the core kernel and enable it on
x86 - preceded by an array of changes. v4.8 saw preparatory changes
in this area already - this is the rest of the work. Includes the
thread stack caching performance optimization. (Andy Lutomirski)
- switch_to() cleanups and all around enhancements. (Brian Gerst)
- A large number of dumpstack infrastructure enhancements and an
unwinder abstraction. The secret long term plan is safe(r) live
patching plus maybe another attempt at debuginfo based unwinding -
but all these current bits are standalone enhancements in a frame
pointer based debug environment as well. (Josh Poimboeuf)
- More __ro_after_init and const annotations. (Kees Cook)
- Enable KASLR for the vmemmap memory region. (Thomas Garnier)"
[ The virtually mapped stack changes are pretty fundamental, and not
x86-specific per se, even if they are only used on x86 right now. ]
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
x86/asm: Get rid of __read_cr4_safe()
thread_info: Use unsigned long for flags
x86/alternatives: Add stack frame dependency to alternative_call_2()
x86/dumpstack: Fix show_stack() task pointer regression
x86/dumpstack: Remove dump_trace() and related callbacks
x86/dumpstack: Convert show_trace_log_lvl() to use the new unwinder
oprofile/x86: Convert x86_backtrace() to use the new unwinder
x86/stacktrace: Convert save_stack_trace_*() to use the new unwinder
perf/x86: Convert perf_callchain_kernel() to use the new unwinder
x86/unwind: Add new unwind interface and implementations
x86/dumpstack: Remove NULL task pointer convention
fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y
sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK
lib/syscall: Pin the task stack in collect_syscall()
x86/process: Pin the target stack in get_wchan()
x86/dumpstack: Pin the target stack when dumping it
kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function
sched/core: Add try_get_task_stack() and put_task_stack()
x86/entry/64: Fix a minor comment rebase error
iommu/amd: Don't put completion-wait semaphore on stack
...
Pull RCU updates from Ingo Molnar:
"The main changes in this cycle were:
- Expedited grace-period changes, most notably avoiding having user
threads drive expedited grace periods, using a workqueue instead.
- Miscellaneous fixes, including a performance fix for lists that was
sent with the lists modifications.
- CPU hotplug updates, most notably providing exact CPU-online
tracking for RCU. This will in turn allow removal of the checks
supporting RCU's prior heuristic that was based on the assumption
that CPUs would take no longer than one jiffy to come online.
- Torture-test updates.
- Documentation updates"
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
list: Expand list_first_entry_or_null()
torture: TOROUT_STRING(): Insert a space between flag and message
rcuperf: Consistently insert space between flag and message
rcutorture: Print out barrier error as document says
torture: Add task state to writer-task stall printk()s
torture: Convert torture_shutdown() to hrtimer
rcutorture: Convert to hotplug state machine
cpu/hotplug: Get rid of CPU_STARTING reference
rcu: Provide exact CPU-online tracking for RCU
rcu: Avoid redundant quiescent-state chasing
rcu: Don't use modular infrastructure in non-modular code
sched: Make wake_up_nohz_cpu() handle CPUs going offline
rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads
rcu: Use RCU's online-CPU state for expedited IPI retry
rcu: Exclude RCU-offline CPUs from expedited grace periods
rcu: Make expedited RCU CPU stall warnings respond to controls
rcu: Stop disabling expedited RCU CPU stall warnings
rcu: Drive expedited grace periods from workqueue
rcu: Consolidate expedited grace period machinery
documentation: Record reason for rcu_head two-byte alignment
...
* pm-cpufreq: (24 commits)
cpufreq: st: add missing \n to end of dev_err message
cpufreq: kirkwood: add missing \n to end of dev_err messages
cpufreq: CPPC: Avoid overflow when calculating desired_perf
cpufreq: ti: Use generic platdev driver
cpufreq: intel_pstate: Add io_boost trace
cpufreq: intel_pstate: Use IOWAIT flag in Atom algorithm
cpufreq: schedutil: Add iowait boosting
cpufreq / sched: SCHED_CPUFREQ_IOWAIT flag to indicate iowait condition
cpufreq: CPPC: Force reporting values in KHz to fix user space interface
cpufreq: create link to policy only for registered CPUs
intel_pstate: constify local structures
cpufreq: dt: Support governor tunables per policy
cpufreq: dt: Update kconfig description
cpufreq: dt: Remove unused code
MAINTAINERS: Add Documentation/cpu-freq/
cpufreq: dt: Add support for r8a7792
cpufreq / sched: ignore SMT when determining max cpu capacity
cpufreq: Drop unnecessary check from cpufreq_policy_alloc()
ARM: multi_v7_defconfig: Don't attempt to enable schedutil governor as module
ARM: exynos_defconfig: Don't attempt to enable schedutil governor as module
...
The code performing irqtime nsecs stats flushing to kcpustat is roughly
the same for hardirq and softirq. So lets consolidate that common code.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-6-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The irqtime accounting currently implement its own ad hoc implementation
of u64_stats API. Lets rather consolidate it with the appropriate
library.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-5-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The callers of the functions performing irqtime kcpustat updates have
IRQS disabled, no need to disable them again.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We can safely use the preempt-unsafe accessors for irqtime when we
flush its counters to kcpustat as IRQs are disabled at this time.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1474849761-12678-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
While going through enqueue/dequeue to review the movement of
set_curr_task() I noticed that the (2nd) update_min_vruntime() call in
dequeue_entity() is suspect.
It turns out, its actually wrong because it will consider
cfs_rq->curr, which could be the entry we just normalized. This mixes
different vruntime forms and leads to fail.
The purpose of the second update_min_vruntime() is to move
min_vruntime forward if the entity we just removed is the one that was
holding it back; _except_ for the DEQUEUE_SAVE case, because then we
know its a temporary removal and it will come back.
However, since we do put_prev_task() _after_ dequeue(), cfs_rq->curr
will still be set (and per the above, can be tranformed into a
different unit), so update_min_vruntime() should also consider
curr->on_rq. This also fixes another corner case where the enqueue
(which also does update_curr()->update_min_vruntime()) happens on the
rq->lock break in schedule(), between dequeue and put_prev_task.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Fixes: 1e87623178 ("sched: Fix ->min_vruntime calculation in dequeue_entity()")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Provide SCHED_WARN_ON as wrapper for WARN_ON_ONCE() to avoid
CONFIG_SCHED_DEBUG wrappery.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Almost all scheduler functions update state with the following
pattern:
if (queued)
dequeue_task(rq, p, DEQUEUE_SAVE);
if (running)
put_prev_task(rq, p);
/* update state */
if (queued)
enqueue_task(rq, p, ENQUEUE_RESTORE);
if (running)
set_curr_task(rq, p);
set_user_nice() however misses the running part, cure this.
This was found by asserting we never enqueue 'current'.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Now that the ia64 only set_curr_task() symbol is gone, provide a
helper just like put_prev_task().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Rename the ia64 only set_curr_task() function to free up the name.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When a task switches to fair scheduling class, the period between now
and the last update of its utilization is accounted as running time
whatever happened during this period. This incorrect accounting applies
to the task and also to the task group branch.
When changing the property of a running task like its list of allowed
CPUs or its scheduling class, we follow the sequence:
- dequeue task
- put task
- change the property
- set task as current task
- enqueue task
The end of the sequence doesn't follow the normal sequence (as per
__schedule()) which is:
- enqueue a task
- then set the task as current task.
This incorrectordering is the root cause of incorrect utilization accounting.
Update the sequence to follow the right one:
- dequeue task
- put task
- change the property
- enqueue task
- set task as current task
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: linaro-kernel@lists.linaro.org
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1473666472-13749-8-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
select_idle_siblings() is a known pain point for a number of
workloads; it either does too much or not enough and sometimes just
does plain wrong.
This rewrite attempts to address a number of issues (but sadly not
all).
The current code does an unconditional sched_domain iteration; with
the intent of finding an idle core (on SMT hardware). The problems
which this patch tries to address are:
- its pointless to look for idle cores if the machine is real busy;
at which point you're just wasting cycles.
- it's behaviour is inconsistent between SMT and !SMT hardware in
that !SMT hardware ends up doing a scan for any idle CPU in the LLC
domain, while SMT hardware does a scan for idle cores and if that
fails, falls back to a scan for idle threads on the 'target' core.
The new code replaces the sched_domain scan with 3 explicit scans:
1) search for an idle core in the LLC
2) search for an idle CPU in the LLC
3) search for an idle thread in the 'target' core
where 1 and 3 are conditional on SMT support and 1 and 2 have runtime
heuristics to skip the step.
Step 1) is conditional on sd_llc_shared->has_idle_cores; when a cpu
goes idle and sd_llc_shared->has_idle_cores is false, we scan all SMT
siblings of the CPU going idle. Similarly, we clear
sd_llc_shared->has_idle_cores when we fail to find an idle core.
Step 2) tracks the average cost of the scan and compares this to the
average idle time guestimate for the CPU doing the wakeup. There is a
significant fudge factor involved to deal with the variability of the
averages. Esp. hackbench was sensitive to this.
Step 3) is unconditional; we assume (also per step 1) that scanning
all SMT siblings in a core is 'cheap'.
With this; SMT systems gain step 2, which cures a few benchmarks --
notably one from Facebook.
One 'feature' of the sched_domain iteration, which we preserve in the
new code, is that it would start scanning from the 'target' CPU,
instead of scanning the cpumask in cpu id order. This avoids multiple
CPUs in the LLC scanning for idle to gang up and find the same CPU
quite as much. The down side is that tasks can end up hopping across
the LLC for no apparent reason.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move the nr_busy_cpus thing from its hacky sd->parent->groups->sgc
location into the much more natural sched_domain_shared location.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since struct sched_domain is strictly per cpu; introduce a structure
that is shared between all 'identical' sched_domains.
Limit to SD_SHARE_PKG_RESOURCES domains for now, as we'll only use it
for shared cache state; if another use comes up later we can easily
relax this.
While the sched_group's are normally shared between CPUs, these are
not natural to use when we need some shared state on a domain level --
since that would require the domain to have a parent, which is not a
given.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There is no point in doing a call_rcu() for each domain, only do a
callback for the root sched domain and clean up the entire set in one
go.
Also make the entire call chain be called destroy_sched_domain*() to
remove confusion with the free_sched_domains() call, which does an
entirely different thing.
Both cpu_attach_domain() callers of destroy_sched_domain() can live
without the call_rcu() because at those points the sched_domain hasn't
been published yet.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Small cleanup; nothing uses the @cpu argument so make it go away.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The partial initialization of wait_queue_t in prepare_to_wait_event() looks
ugly. This was done to shrink .text, but we can simply add the new helper
which does the full initialization and shrink the compiled code a bit more.
And. This way prepare_to_wait_event() can have more users. In particular we
are ready to remove the signal_pending_state() checks from wait_bit_action_f
helpers and change __wait_on_bit_lock() to use prepare_to_wait_event().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160906140055.GA6167@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
__wait_on_bit_lock() doesn't need abort_exclusive_wait() too. Right
now it can't use prepare_to_wait_event() (see the next change), but
it can do the additional finish_wait() if action() fails.
abort_exclusive_wait() no longer has callers, remove it.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160906140053.GA6164@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
___wait_event() doesn't really need abort_exclusive_wait(), we can simply
change prepare_to_wait_event() to remove the waiter from q->task_list if
it was interrupted.
This simplifies the code/logic, and this way prepare_to_wait_event() can
have more users, see the next change.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160908164815.GA18801@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
--
include/linux/wait.h | 7 +------
kernel/sched/wait.c | 35 +++++++++++++++++++++++++----------
2 files changed, 26 insertions(+), 16 deletions(-)
Otherwise this logic only works if mode is "compatible" with another
exclusive waiter.
If some wq has both TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE waiters,
abort_exclusive_wait() won't wait an uninterruptible waiter.
The main user is __wait_on_bit_lock() and currently it is fine but only
because TASK_KILLABLE includes TASK_UNINTERRUPTIBLE and we do not have
lock_page_interruptible() yet.
Just use TASK_NORMAL and remove the "mode" arg from abort_exclusive_wait().
Yes, this means that (say) wake_up_interruptible() can wake up the non-
interruptible waiter(s), but I think this is fine. And in fact I think
that abort_exclusive_wait() must die, see the next change.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160906140047.GA6157@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
2159197d66 ("sched/core: Enable increased load resolution on 64-bit kernels")
we now have two different fixed point units for load:
- 'shares' in calc_cfs_shares() has 20 bit fixed point unit on 64-bit
kernels. Therefore use scale_load() on MIN_SHARES.
- 'wl' in effective_load() has 10 bit fixed point unit. Therefore use
scale_load_down() on tg->shares which has 20 bit fixed point unit on
64-bit kernels.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471874441-24701-1-git-send-email-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Current code can call set_cpu_sibling_map() and invoke sched_set_topology()
more than once (e.g. on CPU hot plug). When this happens after
sched_init_smp() has been called, we lose the NUMA topology extension to
sched_domain_topology in sched_init_numa(). This results in incorrect
topology when the sched domain is rebuilt.
This patch fixes the bug and issues warning if we call sched_set_topology()
after sched_init_smp().
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@suse.de
Cc: jolsa@redhat.com
Cc: rjw@rjwysocki.net
Link: http://lkml.kernel.org/r/1474485552-141429-2-git-send-email-srinivas.pandruvada@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot
(just when they would have exceeded their ideal_runtime).
It makes use of a per-CPU hrtimer resource and hence arming that
hrtimer should be based on total SCHED_FAIR tasks a CPU has across its
various cfs_rqs, rather than being based on number of tasks in a
particular cfs_rq (as implemented currently).
As a result, with current code, its possible for a running task (which
is the sole task in its cfs_rq) to be preempted much after its
ideal_runtime has elapsed, resulting in increased latency for tasks in
other cfs_rq on same CPU.
Fix this by arming sched hrtimer based on total number of SCHED_FAIR
tasks a CPU has across its various cfs_rqs.
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1474075731-11550-1-git-send-email-joonwoop@codeaurora.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
On fully preemptible kernels _cond_resched() is pointless, so avoid
emitting any code for it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Oleg noted that by making do_exit() use __schedule() for the TASK_DEAD
context switch, we can avoid the TASK_DEAD special case currently in
__schedule() because that avoids the extra preempt_disable() from
schedule().
In order to facilitate this, create a do_task_dead() helper which we
place in the scheduler code, such that it can access __schedule().
Also add some __noreturn annotations to the functions, there's no
coming back from do_exit().
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Cheng Chao <cs.os.kernel@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: chris@chris-wilson.co.uk
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20160913163729.GB5012@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In case @cpu == smp_proccessor_id(), we can avoid a sleep+wakeup
cycle by doing a preemption.
Callers such as sched_exec() can benefit from this change.
Signed-off-by: Cheng Chao <cs.os.kernel@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: akpm@linux-foundation.org
Cc: chris@chris-wilson.co.uk
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/1473818510-6779-1-git-send-email-cs.os.kernel@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
We currently keep every task's stack around until the task_struct
itself is freed. This means that we keep the stack allocation alive
for longer than necessary and that, under load, we free stacks in
big batches whenever RCU drops the last task reference. Neither of
these is good for reuse of cache-hot memory, and freeing in batches
prevents us from usefully caching small numbers of vmalloced stacks.
On architectures that have thread_info on the stack, we can't easily
change this, but on architectures that set THREAD_INFO_IN_TASK, we
can free it as soon as the task is dead.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/08ca06cde00ebed0046c5d26cbbf3fbb7ef5b812.1474003868.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull RCU changes from Paul E. McKenney:
- Expedited grace-period changes, most notably avoiding having
user threads drive expedited grace periods, using a workqueue
instead.
- Miscellaneous fixes, including a performance fix for lists
that was sent with the lists modifications (second URL below).
- CPU hotplug updates, most notably providing exact CPU-online
tracking for RCU. This will in turn allow removal of the
checks supporting RCU's prior heuristic that was based on the
assumption that CPUs would take no longer than one jiffy to
come online.
- Torture-test updates.
- Documentation updates.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If an arch opts in by setting CONFIG_THREAD_INFO_IN_TASK_STRUCT,
then thread_info is defined as a single 'u32 flags' and is the first
entry of task_struct. thread_info::task is removed (it serves no
purpose if thread_info is embedded in task_struct), and
thread_info::cpu gets its own slot in task_struct.
This is heavily based on a patch written by Linus.
Originally-from: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jann Horn <jann@thejh.net>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a0898196f0476195ca02713691a5037a14f2aac5.1473801993.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Modify the schedutil cpufreq governor to boost the CPU
frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to
it via cpufreq_update_util().
If that happens, the frequency is set to the maximum during
the first update after receiving the SCHED_CPUFREQ_IOWAIT flag
and then the boost is reduced by half during each following update.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Looks-good-to: Steve Muckle <smuckle@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Testing indicates that it is possible to improve performace
significantly without increasing energy consumption too much by
teaching cpufreq governors to bump up the CPU performance level if
the in_iowait flag is set for the task in enqueue_task_fair().
For this purpose, define a new cpufreq_update_util() flag
SCHED_CPUFREQ_IOWAIT and modify enqueue_task_fair() to pass that
flag to cpufreq_update_util() in the in_iowait case. That generally
requires cpufreq_update_util() to be called directly from there,
because update_load_avg() may not be invoked in that case.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Looks-good-to: Steve Muckle <smuckle@linaro.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
There's a bug in this commit:
97a7142f15 ("sched/fair: Make update_min_vruntime() more readable")
... when !rb_leftmost && curr we fail to advance min_vruntime.
So revert it.
Reported-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The schedstat_val() macro's behavior is kind of surprising: when
schedstat is runtime disabled, it returns zero. Rename it to
schedstat_val_or_zero().
There's also a need for a similar macro which doesn't have the 'if
(schedstat_enable())' check, to avoid doing the check twice. Create a
new 'schedstat_val()' macro for that.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/3bb1d2367d041fee333b0dde17171e709395b675.1466184592.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The schedstat_*() macros are inconsistent: most of them take a pointer
and a field which the macro combines, whereas schedstat_set() takes the
already combined ptr->field.
The already combined ptr->field argument is actually more intuitive and
easier to use, and there's no reason to require the user to split the
variable up, so convert the macros to use the combined argument.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/54953ca25bb579f3a5946432dee409b0e05222c6.1466184592.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
enqueue_sleeper() doesn't actually enqueue, it just handles some
statistics and tracepoints. Rename it to update_stats_enqueue_sleeper()
and call it from update_stats_enqueue().
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/fb20b7159dc4d028c406c0e8d5f8c439b741615b.1466184592.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The dl task will be replenished after dl task timer fire and start a
new period. It will be enqueued and to re-evaluate its dependency on
the tick in order to restart it. However, if the CPU is hot-unplugged,
irq_work_queue will splash since the target CPU is offline.
As a result we get:
WARNING: CPU: 2 PID: 0 at kernel/irq_work.c:69 irq_work_queue_on+0xad/0xe0
Call Trace:
dump_stack+0x99/0xd0
__warn+0xd1/0xf0
warn_slowpath_null+0x1d/0x20
irq_work_queue_on+0xad/0xe0
tick_nohz_full_kick_cpu+0x44/0x50
tick_nohz_dep_set_cpu+0x74/0xb0
enqueue_task_dl+0x226/0x480
activate_task+0x5c/0xa0
dl_task_timer+0x19b/0x2c0
? push_dl_task.part.31+0x190/0x190
This can be triggered by hot-unplugging the full dynticks CPU which dl
task is running on.
We enqueue the dl task on the offline CPU, because we need to do
replenish for start_dl_timer(). So, as Juri pointed out, we would
need to do is calling replenish_dl_entity() directly, instead of
enqueue_task_dl(). pi_se shouldn't be a problem as the task shouldn't
be boosted if it was throttled.
This patch fixes it by avoiding the whole enqueue+dequeue+enqueue story, by
first migrating (set_task_cpu()) and then doing 1 enqueue.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1472639264-3932-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
init_task's preempt_notifiers is initialized twice:
1) sched_init()
-> INIT_HLIST_HEAD(&init_task.preempt_notifiers)
2) sched_init()
-> init_idle(current,) <--- current task is init_task at this time
-> __sched_fork(,current)
-> INIT_HLIST_HEAD(&p->preempt_notifiers)
I think the first one is unnecessary, so remove it.
Signed-off-by: seokhoon.yoon <iamyooon@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471339568-5790-1-git-send-email-iamyooon@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
2159197d66 ("sched/core: Enable increased load resolution on 64-bit kernels")
we now have two different fixed point units for load.
load_above_capacity has to have 10 bits fixed point unit like PELT,
whereas NICE_0_LOAD has 20 bit fixed point unit on 64-bit kernels.
Fix this by scaling down NICE_0_LOAD when multiplying
load_above_capacity with it.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/1470824847-5316-1-git-send-email-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This change goes from heapify() ops done by swapping with parent/child
so that the item to fix moves along, to heapify() ops done by just
pulling the parent/child chain by 1 pos, then storing the item to fix
just at the end. On a non-trivial heapify(), this performs roughly half
stores wrt swaps.
This has been measured to achieve up to 10% of speed-up for cpudl_set()
calls, with a randomly generated workload of 1K,10K,100K random heap
insertions and deletions (75% cpudl_set() calls with is_valid=1 and
25% with is_valid=0), and randomly generated cpu IDs, with up to 256
CPUs, as measured on an Intel Core2 Duo.
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-3-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1. heapify up factored out in new dedicated function heapify_up()
(avoids repetition of same code)
2. call to cpudl_change_key() replaced with heapify_up() when
cpudl_set actually inserts a new node in the heap
3. cpudl_change_key() replaced with heapify() that heapifies up
or down as needed.
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The update_min_vruntime() control flow can be simplified.
Signed-off-by: Byungchul Park <byungchul.park@lge.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: minchan.kim@lge.com
Link: http://lkml.kernel.org/r/1436088829-25768-1-git-send-email-byungchul.park@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The origin of the issue I've seen is related to
a missing memory barrier between check for task->state and
the check for task->on_rq.
The task being woken up is already awake from a schedule()
and is doing the following:
do {
schedule()
set_current_state(TASK_(UN)INTERRUPTIBLE);
} while (!cond);
The waker, actually gets stuck doing the following in
try_to_wake_up():
while (p->on_cpu)
cpu_relax();
Analysis:
The instance I've seen involves the following race:
CPU1 CPU2
while () {
if (cond)
break;
do {
schedule();
set_current_state(TASK_UN..)
} while (!cond);
wakeup_routine()
spin_lock_irqsave(wait_lock)
raw_spin_lock_irqsave(wait_lock) wake_up_process()
} try_to_wake_up()
set_current_state(TASK_RUNNING); ..
list_del(&waiter.list);
CPU2 wakes up CPU1, but before it can get the wait_lock and set
current state to TASK_RUNNING the following occurs:
CPU3
wakeup_routine()
raw_spin_lock_irqsave(wait_lock)
if (!list_empty)
wake_up_process()
try_to_wake_up()
raw_spin_lock_irqsave(p->pi_lock)
..
if (p->on_rq && ttwu_wakeup())
..
while (p->on_cpu)
cpu_relax()
..
CPU3 tries to wake up the task on CPU1 again since it finds
it on the wait_queue, CPU1 is spinning on wait_lock, but immediately
after CPU2, CPU3 got it.
CPU3 checks the state of p on CPU1, it is TASK_UNINTERRUPTIBLE and
the task is spinning on the wait_lock. Interestingly since p->on_rq
is checked under pi_lock, I've noticed that try_to_wake_up() finds
p->on_rq to be 0. This was the most confusing bit of the analysis,
but p->on_rq is changed under runqueue lock, rq_lock, the p->on_rq
check is not reliable without this fix IMHO. The race is visible
(based on the analysis) only when ttwu_queue() does a remote wakeup
via ttwu_queue_remote. In which case the p->on_rq change is not
done uder the pi_lock.
The result is that after a while the entire system locks up on
the raw_spin_irqlock_save(wait_lock) and the holder spins infintely
Reproduction of the issue:
The issue can be reproduced after a long run on my system with 80
threads and having to tweak available memory to very low and running
memory stress-ng mmapfork test. It usually takes a long time to
reproduce. I am trying to work on a test case that can reproduce
the issue faster, but thats work in progress. I am still testing the
changes on my still in a loop and the tests seem OK thus far.
Big thanks to Benjamin and Nick for helping debug this as well.
Ben helped catch the missing barrier, Nick caught every missing
bit in my theory.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
[ Updated comment to clarify matching barriers. Many
architectures do not have a full barrier in switch_to()
so that cannot be relied upon. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nicholas Piggin <nicholas.piggin@gmail.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/e02cce7b-d9ca-1ad0-7a61-ea97c7582b37@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
PELT does not consider SMT when scaling its utilization values via
arch_scale_cpu_capacity(). The value in rq->cpu_capacity_orig does
take SMT into consideration though and therefore may be smaller than
the utilization reported by PELT.
On an Intel i7-3630QM for example rq->cpu_capacity_orig is 589 but
util_avg scales up to 1024. This means that a 50% utilized CPU will show
up in schedutil as ~86% busy.
Fix this by using the same CPU scaling value in schedutil as that which
is used by PELT.
Signed-off-by: Steve Muckle <smuckle@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Now that the x86 switch_to() uses the standard C calling convention,
the STACK_FRAME_NON_STANDARD() annotation is no longer needed.
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1471106302-10159-8-git-send-email-brgerst@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Both timers and hrtimers are maintained on the outgoing CPU until
CPU_DEAD time, at which point they are migrated to a surviving CPU. If a
mod_timer() executes between CPU_DYING and CPU_DEAD time, x86 systems
will splat in native_smp_send_reschedule() when attempting to wake up
the just-now-offlined CPU, as shown below from a NO_HZ_FULL kernel:
[ 7976.741556] WARNING: CPU: 0 PID: 661 at /home/paulmck/public_git/linux-rcu/arch/x86/kernel/smp.c:125 native_smp_send_reschedule+0x39/0x40
[ 7976.741595] Modules linked in:
[ 7976.741595] CPU: 0 PID: 661 Comm: rcu_torture_rea Not tainted 4.7.0-rc2+ #1
[ 7976.741595] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
[ 7976.741595] 0000000000000000 ffff88000002fcc8 ffffffff8138ab2e 0000000000000000
[ 7976.741595] 0000000000000000 ffff88000002fd08 ffffffff8105cabc 0000007d1fd0ee18
[ 7976.741595] 0000000000000001 ffff88001fd16d40 ffff88001fd0ee00 ffff88001fd0ee00
[ 7976.741595] Call Trace:
[ 7976.741595] [<ffffffff8138ab2e>] dump_stack+0x67/0x99
[ 7976.741595] [<ffffffff8105cabc>] __warn+0xcc/0xf0
[ 7976.741595] [<ffffffff8105cb98>] warn_slowpath_null+0x18/0x20
[ 7976.741595] [<ffffffff8103cba9>] native_smp_send_reschedule+0x39/0x40
[ 7976.741595] [<ffffffff81089bc2>] wake_up_nohz_cpu+0x82/0x190
[ 7976.741595] [<ffffffff810d275a>] internal_add_timer+0x7a/0x80
[ 7976.741595] [<ffffffff810d3ee7>] mod_timer+0x187/0x2b0
[ 7976.741595] [<ffffffff810c89dd>] rcu_torture_reader+0x33d/0x380
[ 7976.741595] [<ffffffff810c66f0>] ? sched_torture_read_unlock+0x30/0x30
[ 7976.741595] [<ffffffff810c86a0>] ? rcu_bh_torture_read_lock+0x80/0x80
[ 7976.741595] [<ffffffff8108068f>] kthread+0xdf/0x100
[ 7976.741595] [<ffffffff819dd83f>] ret_from_fork+0x1f/0x40
[ 7976.741595] [<ffffffff810805b0>] ? kthread_create_on_node+0x200/0x200
However, in this case, the wakeup is redundant, because the timer
migration will reprogram timer hardware as needed. Note that the fact
that preemption is disabled does not avoid the splat, as the offline
operation has already passed both the synchronize_sched() and the
stop_machine() that would be blocked by disabled preemption.
This commit therefore modifies wake_up_nohz_cpu() to avoid attempting
to wake up offline CPUs. It also adds a comment stating that the
caller must tolerate lost wakeups when the target CPU is going offline,
and suggesting the CPU_DEAD notifier as a recovery mechanism.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Commit:
d670ec1317 ("posix-cpu-timers: Cure SMP wobbles")
started accounting thread group tasks pending runtime in thread_group_cputime().
Another commit:
6e998916df ("sched/cputime: Fix clock_nanosleep()/clock_gettime() inconsistency")
updated scheduler runtime statistics (call update_curr()) when reading task pending
runtime. Those changes cause bad performance of SYS_times() and
SYS_clock_gettimes(CLOCK_PROCESS_CPUTIME_ID) syscalls, especially on
larger systems with many CPUs.
While we would like to have cpuclock monotonicity kept i.e. have
problems fixed by above commits stay fixed, we also would like to have
good performance.
However when we notice that change from commit d670ec1317 is not
longer needed to solve problem addressed by that commit, because of
change from the second commit 6e998916df, we can get room for
optimization. Since we update task while reading it's pending runtime
in task_sched_runtime(), clock_gettime(CLOCK_PROCESS_CPUTIME_ID) will
see updated values and on testcase from d670ec1317 process cpuclock
will not be smaller than thread cpuclock.
I tested the patch on testcases from commits d670ec1317,
6e998916df and some other cpuclock/cputimers testcases and
did not found cpuclock monotonicity problems or other malfunction.
This patch has the drawback that we will not provide thread group cputime
up-to-date to the last moment. For example when arming cputime timer,
we will arm it with possibly a bit outdated values and that timer will
trigger earlier compared to behaviour without the patch. However that
was the behaviour before d670ec1317 commit (kernel v3.1) so it's
unlikely to affect applications.
Patch improves related syscall performance, as measured by Giovanni's
benchmarks described in commit:
6075620b05 ("sched/cputime: Mitigate performance regression in times()/clock_gettime()")
The benchmark results are:
SYS_clock_gettime():
threads 4.7-rc7 3.18-rc3 4.7-rc7 + prefetch 4.7-rc7 + patch
(pre-6e998916dfe3)
2 3.48 2.23 ( 35.68%) 3.06 ( 11.83%) 1.08 ( 68.81%)
5 3.33 2.83 ( 14.84%) 3.25 ( 2.40%) 0.71 ( 78.55%)
8 3.37 2.84 ( 15.80%) 3.26 ( 3.30%) 0.56 ( 83.49%)
12 3.32 3.09 ( 6.69%) 3.37 ( -1.60%) 0.42 ( 87.28%)
21 4.01 3.14 ( 21.70%) 3.90 ( 2.74%) 0.35 ( 91.35%)
30 3.63 3.28 ( 9.75%) 3.36 ( 7.41%) 0.28 ( 92.23%)
48 3.71 3.02 ( 18.69%) 3.11 ( 16.27%) 0.39 ( 89.39%)
79 3.75 2.88 ( 23.23%) 3.16 ( 15.74%) 0.46 ( 87.76%)
110 3.81 2.95 ( 22.62%) 3.25 ( 14.80%) 0.56 ( 85.41%)
128 3.88 3.05 ( 21.28%) 3.31 ( 14.76%) 0.62 ( 84.10%)
SYS_times():
threads 4.7-rc7 3.18-rc3 4.7-rc7 + prefetch 4.7-rc7 + patch
(pre-6e998916dfe3)
2 3.65 2.27 ( 37.94%) 3.25 ( 11.03%) 1.62 ( 55.71%)
5 3.45 2.78 ( 19.34%) 3.17 ( 7.92%) 2.33 ( 32.28%)
8 3.52 2.79 ( 20.66%) 3.22 ( 8.69%) 2.06 ( 41.44%)
12 3.29 3.02 ( 8.33%) 3.36 ( -2.04%) 2.00 ( 39.18%)
21 4.07 3.10 ( 23.86%) 3.92 ( 3.78%) 2.07 ( 49.18%)
30 3.87 3.33 ( 13.80%) 3.40 ( 12.17%) 1.89 ( 51.12%)
48 3.79 2.96 ( 21.94%) 3.16 ( 16.61%) 1.69 ( 55.46%)
79 3.88 2.88 ( 25.82%) 3.28 ( 15.42%) 1.60 ( 58.81%)
110 3.90 2.98 ( 23.73%) 3.38 ( 13.35%) 1.73 ( 55.61%)
128 4.00 3.10 ( 22.40%) 3.38 ( 15.45%) 1.66 ( 58.52%)
Reported-and-tested-by: Giovanni Gherdovich <ggherdovich@suse.cz>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Galbraith <mgalbraith@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/20160817093043.GA25206@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently, SD_WAKE_AFFINE always takes priority over wakeup balancing if
SD_BALANCE_WAKE is set on the sched_domains. For asymmetric
configurations SD_WAKE_AFFINE is only desirable if the waking task's
compute demand (utilization) is suitable for the waking CPU and the
previous CPU, and all CPUs within their respective
SD_SHARE_PKG_RESOURCES domains (sd_llc). If not, let wakeup balancing
take over (find_idlest_{group, cpu}()).
This patch makes affine wake-ups conditional on whether both the waker
CPU and the previous CPU has sufficient capacity for the waking task,
or not, assuming that the CPU capacities within an SD_SHARE_PKG_RESOURCES
domain (sd_llc) are homogeneous.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-10-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
To be able to compare the capacity of the target CPU with the highest
available CPU capacity, store the maximum per-CPU capacity in the root
domain.
The max per-CPU capacity should be 1024 for all systems except SMT,
where the capacity is currently based on smt_gain and the number of
hardware threads and is <1024. If SMT can be brought to work with a
per-thread capacity of 1024, this patch can be dropped and replaced by a
hard-coded max capacity of 1024 (=SCHED_CAPACITY_SCALE).
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/26c69258-9947-f830-a53e-0c54e7750646@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
A domain with the SD_ASYM_CPUCAPACITY flag set indicate that
sched_groups at this level and below do not include CPUs of all
capacities available (e.g. group containing little-only or big-only CPUs
in big.LITTLE systems). It is therefore necessary to put in more effort
in finding an appropriate CPU at task wake-up by enabling balancing at
wake-up (SD_BALANCE_WAKE) on all lower (child) levels.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-8-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add a topology flag to the sched_domain hierarchy indicating the lowest
domain level where the full range of CPU capacities is represented by
the domain members for asymmetric capacity topologies (e.g. ARM
big.LITTLE).
The flag is intended to indicate that extra care should be taken when
placing tasks on CPUs and this level spans all the different types of
CPUs found in the system (no need to look further up the domain
hierarchy). This information is currently only available through
iterating through the capacities of all the CPUs at parent levels in the
sched_domain hierarchy.
SD 2 [ 0 1 2 3] SD_ASYM_CPUCAPACITY
SD 1 [ 0 1] [ 2 3] !SD_ASYM_CPUCAPACITY
CPU: 0 1 2 3
capacity: 756 756 1024 1024
If the topology in the example above is duplicated to create an eight
CPU example with third sched_domain level on top (SD 3), this level
should not have the flag set (!SD_ASYM_CPUCAPACITY) as its two group
would both have all CPU capacities represented within them.
Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dietmar.eggemann@arm.com
Cc: freedom.tan@mediatek.com
Cc: keita.kobayashi.ym@renesas.com
Cc: mgalbraith@suse.de
Cc: sgurrappadi@nvidia.com
Cc: vincent.guittot@linaro.org
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1469453670-2660-6-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit:
5743021831 ("sched/cputime: Count actually elapsed irq & softirq time")
... fixed a bug but also triggered a regression:
On an i5 laptop, 4 pCPUs, 4vCPUs for one full dynticks guest, there are four
CPU hog processes(for loop) running in the guest, I hot-unplug the pCPUs
on host one by one until there is only one left, then observe CPU utilization
via 'top' in the guest, it shows:
100% st for cpu0(housekeeping)
75% st for other CPUs (nohz full mode)
However, w/o this commit it shows the correct 75% for all four CPUs.
When a guest is interrupted for a longer amount of time, missed clock ticks
are not redelivered later. Because of that, we should not limit the amount
of steal time accounted to the amount of time that the calling functions
think have passed.
However, the interval returned by account_other_time() is NOT rounded down
to the nearest jiffy, while the base interval in get_vtime_delta() it is
subtracted from is, so the max cputime limit is required to avoid underflow.
This patch fixes the regression by limiting the account_other_time() from
get_vtime_delta() to avoid underflow, and lets the other three call sites
(in account_other_time() and steal_account_process_time()) account however
much steal time the host told us elapsed.
Suggested-by: Rik van Riel <riel@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krcmar <rkrcmar@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/r/1471399546-4069-1-git-send-email-wanpeng.li@hotmail.com
[ Improved the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The nohz_stamp member of struct rq has been unused since 2010,
when this commit removed the code that referenced it:
396e894d28 ("sched: Revert nohz_ratelimit() for now")
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20160815121410.5ea1c98f@annuminas.surriel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Mike reports:
Roughly 10% of the time, ltp testcase getrusage04 fails:
getrusage04 0 TINFO : Expected timers granularity is 4000 us
getrusage04 0 TINFO : Using 1 as multiply factor for max [us]time increment (1000+4000us)!
getrusage04 0 TINFO : utime: 0us; stime: 179us
getrusage04 0 TINFO : utime: 3751us; stime: 0us
getrusage04 1 TFAIL : getrusage04.c:133: stime increased > 5000us:
And tracked it down to the case where the task simply doesn't get
_any_ [us]time ticks.
Update the code to assume all rtime is utime when we lack information,
thus ensuring a task that elides the tick gets time accounted.
Reported-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Tested-by: Mike Galbraith <umgwanakikbuti@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Fredrik Markstrom <fredrik.markstrom@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: stable@vger.kernel.org # 4.3+
Fixes: 9d7fb04276 ("sched/cputime: Guarantee stime + utime == rtime")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All of the callers of cpufreq_update_util() pass rq_clock(rq) to it
as the time argument and some of them check whether or not cpu_of(rq)
is equal to smp_processor_id() before calling it, so rework it to
take a runqueue pointer as the argument and move the rq_clock(rq)
evaluation into it.
Additionally, provide a wrapper checking cpu_of(rq) against
smp_processor_id() for the cpufreq_update_util() callers that
need it.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
It is useful to know the reason why cpufreq_update_util() has just
been called and that can be passed as flags to cpufreq_update_util()
and to the ->func() callback in struct update_util_data. However,
doing that in addition to passing the util and max arguments they
already take would be clumsy, so avoid it.
Instead, use the observation that the schedutil governor is part
of the scheduler proper, so it can access scheduler data directly.
This allows the util and max arguments of cpufreq_update_util()
and the ->func() callback in struct update_util_data to be replaced
with a flags one, but schedutil has to be modified to follow.
Thus make the schedutil governor obtain the CFS utilization
information from the scheduler and use the "RT" and "DL" flags
instead of the special utilization value of ULONG_MAX to track
updates from the RT and DL sched classes. Make it non-modular
too to avoid having to export scheduler variables to modules at
large.
Next, update all of the other users of cpufreq_update_util()
and the ->func() callback in struct update_util_data accordingly.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Commit:
f9bcf1e0e0 ("sched/cputime: Fix steal time accounting")
... fixes a leak on steal time accounting but forgets to account
the ticks passed in parameters, assuming there is only one to
take into account.
Let's consider that parameter back.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Wanpeng Li <kernellwp@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: linux-tip-commits@vger.kernel.org
Link: http://lkml.kernel.org/r/20160811125822.GB4214@lerouge
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit:
5743021831 ("sched/cputime: Count actually elapsed irq & softirq time")
... didn't take steal time into consideration with passing the noirqtime
kernel parameter.
As Paolo pointed out before:
| Why not? If idle=poll, for example, any time the guest is suspended (and
| thus cannot poll) does count as stolen time.
This patch fixes it by reducing steal time from idle time accounting when
the noirqtime parameter is true. The average idle time drops from 56.8%
to 54.75% for nohz idle kvm guest(noirqtime, idle=poll, four vCPUs running
on one pCPU).
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1470893795-3527-1-git-send-email-wanpeng.li@hotmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
cgroup_path() and friends used to format the path from the end and
thus the resulting path usually didn't start at the start of the
passed in buffer. Also, when the buffer was too small, the partial
result was truncated from the head rather than tail and there was no
way to tell how long the full path would be. These make the functions
less robust and more awkward to use.
With recent updates to kernfs_path(), cgroup_path() and friends can be
made to behave in strlcpy() style.
* cgroup_path(), cgroup_path_ns[_locked]() and task_cgroup_path() now
always return the length of the full path. If buffer is too small,
it contains nul terminated truncated output.
* All users updated accordingly.
v2: cgroup_path() usage in kernel/sched/debug.c converted.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
This message is currently really useless since it always prints a value
that comes from the printk() we just did, e.g.:
BUG: sleeping function called from invalid context at mm/slab.h:388
in_atomic(): 0, irqs_disabled(): 0, pid: 31996, name: trinity-c1
Preemption disabled at:[<ffffffff8119db33>] down_trylock+0x13/0x80
BUG: sleeping function called from invalid context at include/linux/freezer.h:56
in_atomic(): 0, irqs_disabled(): 0, pid: 31996, name: trinity-c1
Preemption disabled at:[<ffffffff811aaa37>] console_unlock+0x2f7/0x930
Here, both down_trylock() and console_unlock() is somewhere in the
printk() path.
We should save the value before calling printk() and use the saved value
instead. That immediately reveals the offending callsite:
BUG: sleeping function called from invalid context at mm/slab.h:388
in_atomic(): 0, irqs_disabled(): 0, pid: 14971, name: trinity-c2
Preemption disabled at:[<ffffffff819bcd46>] rhashtable_walk_start+0x46/0x150
Bug report:
http://marc.info/?l=linux-netdev&m=146925979821849&w=2
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russel <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
setup_new_dl_entity() takes two parameters, but it only actually uses
one of them, under a different name, to setup a new dl_entity, after:
2f9f3fdc928 "sched/deadline: Remove dl_new from struct sched_dl_entity"
as we currently do:
setup_new_dl_entity(&p->dl, &p->dl)
However, before Luca's change we were doing:
setup_new_dl_entity(dl_se, pi_se)
in update_dl_entity() for a dl_se->new entity: we were using pi_se's
parameters (the potential PI donor) for setting up a new entity.
This change removes the useless second parameter of setup_new_dl_entity().
While we are at it we also optimize things further calling setup_new_dl_
entity() only for already queued tasks, since (as pointed out by Xunlei)
we already do the very same update at tasks wakeup time anyway. By doing
so, we don't need to worry about a potential PI donor anymore, as
rt_mutex_setprio() takes care of that already for us.
Signed-off-by: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luca Abeni <luca.abeni@unitn.it>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Xunlei Pang <xpang@redhat.com>
Link: http://lkml.kernel.org/r/1470409675-20935-1-git-send-email-juri.lelli@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
