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sched: fix sync wakeups

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Pawel Dziekonski reported that the openssl benchmark and his
quantum chemistry application both show slowdowns due to the
scheduler under-parallelizing execution.

The reason are pipe wakeups still doing 'sync' wakeups which
overrides the normal buddy wakeup logic - even if waker and
wakee are loosely coupled.

Fix an inversion of logic in the buddy wakeup code.

Reported-by: Pawel Dziekonski <dzieko@gmail.com>
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 2009-01-26 17:56:17 +01:00 committed by Ingo Molnar
parent f90d4118ba
commit d942fb6c7d
2 changed files with 6 additions and 9 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
kernel/sched.c
View file

@ -2266,6 +2266,10 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync)
if (!sched_feat(SYNC_WAKEUPS)) if (!sched_feat(SYNC_WAKEUPS))
sync = 0; sync = 0;
if (!sync && (current->se.avg_overlap < sysctl_sched_migration_cost &&
p->se.avg_overlap < sysctl_sched_migration_cost))
sync = 1;
#ifdef CONFIG_SMP #ifdef CONFIG_SMP
if (sched_feat(LB_WAKEUP_UPDATE)) { if (sched_feat(LB_WAKEUP_UPDATE)) {
struct sched_domain *sd; struct sched_domain *sd;

11
kernel/sched_fair.c
View file

@ -1179,20 +1179,15 @@ wake_affine(struct sched_domain *this_sd, struct rq *this_rq,
int idx, unsigned long load, unsigned long this_load, int idx, unsigned long load, unsigned long this_load,
unsigned int imbalance) unsigned int imbalance)
{ {
struct task_struct *curr = this_rq->curr;
struct task_group *tg;
unsigned long tl = this_load; unsigned long tl = this_load;
unsigned long tl_per_task; unsigned long tl_per_task;
struct task_group *tg;
unsigned long weight; unsigned long weight;
int balanced; int balanced;
if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS)) if (!(this_sd->flags & SD_WAKE_AFFINE) || !sched_feat(AFFINE_WAKEUPS))
return 0; return 0;
if (sync && (curr->se.avg_overlap > sysctl_sched_migration_cost ||
p->se.avg_overlap > sysctl_sched_migration_cost))
sync = 0;
/* /*
* If sync wakeup then subtract the (maximum possible) * If sync wakeup then subtract the (maximum possible)
* effect of the currently running task from the load * effect of the currently running task from the load
@ -1419,9 +1414,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
if (!sched_feat(WAKEUP_PREEMPT)) if (!sched_feat(WAKEUP_PREEMPT))
return; return;
if (sched_feat(WAKEUP_OVERLAP) && (sync || if (sched_feat(WAKEUP_OVERLAP) && sync) {
(se->avg_overlap < sysctl_sched_migration_cost &&
pse->avg_overlap < sysctl_sched_migration_cost))) {
resched_task(curr); resched_task(curr);
return; return;
} }