linux/kernel/sched
Vincent Guittot a4c3c04974 sched/fair: Update and fix the runnable propagation rule
Unlike running, the runnable part can't be directly propagated through
the hierarchy when we migrate a task. The main reason is that runnable
time can be shared with other sched_entities that stay on the rq and
this runnable time will also remain on prev cfs_rq and must not be
removed.

Instead, we can estimate what should be the new runnable of the prev
cfs_rq and check that this estimation stay in a possible range. The
prop_runnable_sum is a good estimation when adding runnable_sum but
fails most often when we remove it. Instead, we could use the formula
below instead:

  gcfs_rq's runnable_sum = gcfs_rq->avg.load_sum / gcfs_rq->load.weight

which assumes that tasks are equally runnable which is not true but
easy to compute.

Beside these estimates, we have several simple rules that help us to filter
out wrong ones:

 - ge->avg.runnable_sum <= than LOAD_AVG_MAX
 - ge->avg.runnable_sum >= ge->avg.running_sum (ge->avg.util_sum << LOAD_AVG_MAX)
 - ge->avg.runnable_sum can't increase when we detach a task

The effect of these fixes is better cgroups balancing.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Chris Mason <clm@fb.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yuyang Du <yuyang.du@intel.com>
Link: http://lkml.kernel.org/r/1510842112-21028-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-12-06 19:30:50 +01:00
..
autogroup.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
autogroup.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
clock.c sched/clock, sched/cputime: Use lockdep to assert IRQs are disabled/enabled 2017-11-08 11:13:53 +01:00
completion.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
core.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
cpuacct.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpudeadline.c sched/deadline: Change return value of cpudl_find() 2017-08-10 12:18:17 +02:00
cpudeadline.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cpufreq_schedutil.c cpufreq: schedutil: Reset cached_raw_freq when not in sync with next_freq 2017-11-08 23:59:33 +01:00
cpufreq.c cpufreq / sched: Pass flags to cpufreq_update_util() 2016-08-16 22:14:55 +02:00
cpupri.c sched/cpupri: Don't re-initialize 'struct cpupri' 2017-08-10 12:18:14 +02:00
cpupri.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
cputime.c Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-11-15 14:29:44 -08:00
deadline.c Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-11-15 14:29:44 -08:00
debug.c sched/fair: Propagate an effective runnable_load_avg 2017-09-29 19:35:15 +02:00
fair.c sched/fair: Update and fix the runnable propagation rule 2017-12-06 19:30:50 +01:00
features.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
idle_task.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
idle.c sched/idle: Micro-optimize the idle loop 2017-10-26 08:31:29 +02:00
isolation.c sched/isolation: Add basic isolcpus flags 2017-10-27 09:55:31 +02:00
loadavg.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Makefile Merge branch 'linus' into sched/core, to pick up fixes 2017-11-08 10:17:15 +01:00
membarrier.c membarrier: Provide register expedited private command 2017-10-19 22:13:40 -04:00
rt.c Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-11-15 14:29:44 -08:00
sched-pelt.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sched.h Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-11-15 14:29:44 -08:00
stats.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stats.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stop_task.c Merge branch 'for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-11-15 14:29:44 -08:00
swait.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
topology.c Merge branch 'linus' into sched/core, to pick up fixes 2017-11-08 10:17:15 +01:00
wait_bit.c Pass mode to wait_on_atomic_t() action funcs and provide default actions 2017-11-13 15:38:16 +00:00
wait.c sched/wait: Fix add_wait_queue() behavioral change 2017-12-06 19:30:34 +01:00