Commit 002f128b authored Apr 08, 2009 by Paul Turner Committed by Ingo Molnar Apr 09, 2009

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>

parent e3c8ca83

kernel/sched_fair.c

+3 −10

Original line number	Diff line number	Diff line
		@@ -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);

		if (wakeup_preempt_entity(se, pse) == 1) {
		if (wakeup_preempt_entity(se, pse) == 1)
		resched_task(curr);
		break;
		}

		se = parent_entity(se);
		pse = parent_entity(pse);
		}
		}

		static struct task_struct pick_next_task_fair(struct rq rq)