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Groups > linux.kernel > #1405243
| From | Morten Rasmussen <morten.rasmussen@arm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide |
| Date | 2016-05-23 13:00 +0200 |
| Message-ID | <rBVKy-4Lf-31@gated-at.bofh.it> (permalink) |
| References | <rBVKx-4Lf-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
wake_wide() is based on task wakee_flips of the waker and the wakee to decide whether an affine wakeup is desirable. On lightly loaded systems the waker is frequently the idle task (pid=0) which can accumulate a lot of wakee_flips in that scenario. It makes little sense to prevent affine wakeups on an idle cpu due to the idle task wakee_flips, so it makes more sense to ignore them in wake_wide(). cc: Ingo Molnar <mingo@redhat.com> cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com> --- kernel/sched/fair.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c49e25a..0fe3020 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -5007,6 +5007,10 @@ static int wake_wide(struct task_struct *p) unsigned int slave = p->wakee_flips; int factor = this_cpu_read(sd_llc_size); + /* Don't let the idle task prevent affine wakeups */ + if (is_idle_task(current)) + return 0; + if (master < slave) swap(master, slave); if (slave < factor || master < slave * factor) -- 1.9.1
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[PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Morten Rasmussen <morten.rasmussen@arm.com> - 2016-05-23 13:00 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Mike Galbraith <mgalbraith@suse.de> - 2016-05-23 13:20 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Morten Rasmussen <morten.rasmussen@arm.com> - 2016-05-23 14:00 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Mike Galbraith <mgalbraith@suse.de> - 2016-05-23 15:10 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Morten Rasmussen <morten.rasmussen@arm.com> - 2016-05-23 16:20 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Mike Galbraith <mgalbraith@suse.de> - 2016-05-23 17:50 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Yuyang Du <yuyang.du@intel.com> - 2016-05-24 09:20 +0200
Re: [PATCH 03/16] sched/fair: Disregard idle task wakee_flips in wake_wide Yuyang Du <yuyang.du@intel.com> - 2016-05-24 09:10 +0200
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