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sched: sync wakeups vs avg_overlap

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While looking at the code I wondered why we always do:

  sync && avg_overlap < migration_cost

Which is a bit odd, since the overlap test was meant to detect sync wakeups
so using it to specialize sync wakeups doesn't make much sense.

Hence change the code to do:

  sync || avg_overlap < migration_cost

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-10-08 09:16:04 +02:00 committed by Ingo Molnar
parent 990d0f2ced
commit 2fb7635c4c
1 changed files with 10 additions and 8 deletions
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18
kernel/sched_fair.c
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@ -1103,6 +1103,11 @@ wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
return 0;
if (!sync && sched_feat(SYNC_WAKEUPS) &&
curr->se.avg_overlap < sysctl_sched_migration_cost &&
p->se.avg_overlap < sysctl_sched_migration_cost)
sync = 1;
/*
* If sync wakeup then subtract the (maximum possible)
* effect of the currently running task from the load
@ -1127,11 +1132,8 @@ wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
* a reasonable amount of time then attract this newly
* woken task:
*/
if (sync && balanced) {
if (curr->se.avg_overlap < sysctl_sched_migration_cost &&
p->se.avg_overlap < sysctl_sched_migration_cost)
return 1;
}
if (sync && balanced)
return 1;
schedstat_inc(p, se.nr_wakeups_affine_attempts);
tl_per_task = cpu_avg_load_per_task(this_cpu);
@ -1268,9 +1270,9 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
if (!sched_feat(WAKEUP_PREEMPT))
return;
if (sched_feat(WAKEUP_OVERLAP) && sync &&
se->avg_overlap < sysctl_sched_migration_cost &&
pse->avg_overlap < sysctl_sched_migration_cost) {
if (sched_feat(WAKEUP_OVERLAP) && (sync ||
(se->avg_overlap < sysctl_sched_migration_cost &&
pse->avg_overlap < sysctl_sched_migration_cost))) {
resched_task(curr);
return;
}