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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> |
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.. | ||
auto_group.c | ||
auto_group.h | ||
clock.c | ||
completion.c | ||
core.c | ||
cpuacct.c | ||
cpuacct.h | ||
cpudeadline.c | ||
cpudeadline.h | ||
cpufreq_schedutil.c | ||
cpufreq.c | ||
cpupri.c | ||
cpupri.h | ||
cputime.c | ||
deadline.c | ||
debug.c | ||
fair.c | ||
features.h | ||
idle_task.c | ||
idle.c | ||
loadavg.c | ||
Makefile | ||
rt.c | ||
sched.h | ||
stats.c | ||
stats.h | ||
stop_task.c | ||
swait.c | ||
wait.c |