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sched: remove redundant hierarchy walk in check_preempt_wakeup 

Impact: micro-optimization

Under group scheduling we traverse up until we are at common siblings
to make the wakeup comparison on.

At this point however, they should have the same parent so continuing
to check up the tree is redundant.

Signed-off-by: Paul Turner <pjt@google.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <alpine.DEB.1.00.0904081520320.30317@kitami.corp.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Paul Turner 2009-04-08 15:29:43 -07:00 committed by Ingo Molnar
parent e3c8ca8336
commit 002f128b47
1 changed files with 3 additions and 10 deletions
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13
kernel/sched_fair.c
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@ -1487,17 +1487,10 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int sync)
find_matching_se(&se, &pse);
while (se) {
BUG_ON(!pse);
BUG_ON(!pse);
if (wakeup_preempt_entity(se, pse) == 1) {
resched_task(curr);
break;
}
se = parent_entity(se);
pse = parent_entity(pse);
}
if (wakeup_preempt_entity(se, pse) == 1)
resched_task(curr);
}
static struct task_struct *pick_next_task_fair(struct rq *rq)