luck/tmp_suning_uos_patched
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sched: clear buddies more aggressively

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It was noticed that a task could get re-elected past its run quota due to buddy
affinities. This could increase latency a little. Cure it by more aggresively
clearing buddy state.

We do so in two situations:
 - when we force preempt
 - when we select a buddy to run

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mike Galbraith 2009-01-28 14:51:39 +01:00 committed by Ingo Molnar
parent 1596e29773
commit a9f3e2b549
1 changed files with 12 additions and 1 deletions
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13
kernel/sched_fair.c
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@ -768,8 +768,14 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
ideal_runtime = sched_slice(cfs_rq, curr); ideal_runtime = sched_slice(cfs_rq, curr);
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
if (delta_exec > ideal_runtime) if (delta_exec > ideal_runtime) {
resched_task(rq_of(cfs_rq)->curr); resched_task(rq_of(cfs_rq)->curr);
/*
* The current task ran long enough, ensure it doesn't get
* re-elected due to buddy favours.
*/
clear_buddies(cfs_rq, curr);
}
} }
static void static void
@ -1445,6 +1451,11 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
do { do {
se = pick_next_entity(cfs_rq); se = pick_next_entity(cfs_rq);
/*
* If se was a buddy, clear it so that it will have to earn
* the favour again.
*/
clear_buddies(cfs_rq, se);
set_next_entity(cfs_rq, se); set_next_entity(cfs_rq, se);
cfs_rq = group_cfs_rq(se); cfs_rq = group_cfs_rq(se);
} while (cfs_rq); } while (cfs_rq);