linux/kernel/sched
Morten Rasmussen 104cb16d9e sched/fair: Compute task/cpu utilization at wake-up correctly
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>
2016-11-16 10:29:05 +01:00
..
auto_group.c sched/core: Move the sched_to_prio[] arrays out of line 2015-12-04 10:34:46 +01:00
auto_group.h sched, timer: Convert usages of ACCESS_ONCE() in the scheduler to READ_ONCE()/WRITE_ONCE() 2015-05-08 12:11:32 +02:00
clock.c sched/clock: Make local_clock()/cpu_clock() inline 2016-04-13 12:25:22 +02:00
completion.c sched/completion: Serialize completion_done() with complete() 2015-02-18 14:27:40 +01:00
core.c Merge branch 'linus' into sched/core, to pick up fixes 2016-11-11 08:27:11 +01:00
cpuacct.c sched/cpuacct: Avoid %lld seq_printf warning 2016-11-16 10:29:03 +01:00
cpuacct.h sched/cpuacct: Simplify the cpuacct code 2016-03-21 11:00:28 +01:00
cpudeadline.c sched/deadline: Split cpudl_set() into cpudl_set() and cpudl_clear() 2016-09-05 13:29:43 +02:00
cpudeadline.h sched/deadline: Split cpudl_set() into cpudl_set() and cpudl_clear() 2016-09-05 13:29:43 +02:00
cpufreq_schedutil.c cpufreq: schedutil: Add iowait boosting 2016-09-13 23:36:01 +02:00
cpufreq.c cpufreq / sched: Pass flags to cpufreq_update_util() 2016-08-16 22:14:55 +02:00
cpupri.c sched/core: Use tsk_cpus_allowed() instead of accessing ->cpus_allowed 2016-05-12 09:55:35 +02:00
cpupri.h sched/cpupri: Remove unnecessary definitions in cpupri.h 2014-11-16 10:58:59 +01:00
cputime.c sched/cputime: Simplify task_cputime() 2016-11-15 09:51:05 +01:00
deadline.c sched/deadline: Fix typo in a comment 2016-11-11 08:28:52 +01:00
debug.c Merge branch 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-10-14 12:18:50 -07:00
fair.c sched/fair: Compute task/cpu utilization at wake-up correctly 2016-11-16 10:29:05 +01:00
features.h sched/fair: Convert arch_scale_cpu_capacity() from weak function to #define 2015-09-13 09:52:55 +02:00
idle_task.c sched/core: Rewrite and improve select_idle_siblings() 2016-09-30 11:03:09 +02:00
idle.c nmi_backtrace: generate one-line reports for idle cpus 2016-10-07 18:46:30 -07:00
loadavg.c sched/core: Correct off by one bug in load migration calculation 2016-07-13 14:58:20 +02:00
Makefile cpufreq: schedutil: New governor based on scheduler utilization data 2016-04-02 01:09:12 +02:00
rt.c cpufreq / sched: Pass runqueue pointer to cpufreq_update_util() 2016-08-16 22:16:03 +02:00
sched.h Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-03 16:13:28 -07:00
stats.c sched: use %*pb[l] to print bitmaps including cpumasks and nodemasks 2015-02-13 21:21:37 -08:00
stats.h sched/debug: Rename 'schedstat_val()' -> 'schedstat_val_or_zero()' 2016-09-05 13:29:46 +02:00
stop_task.c locking/lockdep, sched/core: Implement a better lock pinning scheme 2016-05-05 09:23:59 +02:00
swait.c wait.[ch]: Introduce the simple waitqueue (swait) implementation 2016-02-25 11:27:16 +01:00
wait.c mm: remove per-zone hashtable of bitlock waitqueues 2016-10-27 09:27:57 -07:00