Messages in this thread Patch in this message | | | Date | Sat, 18 Jul 2009 14:21:31 GMT | From | tip-bot for Frederic Weisbecker <> | Subject | [tip:sched/core] sched: Drop the need_resched() loop from cond_resched() |
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Commit-ID: e7aaaa6934636d7a6cadd9e2a05250fbb6a34f65 Gitweb: http://git.kernel.org/tip/e7aaaa6934636d7a6cadd9e2a05250fbb6a34f65 Author: Frederic Weisbecker <fweisbec@gmail.com> AuthorDate: Thu, 16 Jul 2009 15:44:29 +0200 Committer: Ingo Molnar <mingo@elte.hu> CommitDate: Sat, 18 Jul 2009 15:51:38 +0200
sched: Drop the need_resched() loop from cond_resched()
The schedule() function is a loop that reschedules the current task while the TIF_NEED_RESCHED flag is set:
void schedule(void) { need_resched: /* schedule code */ if (need_resched()) goto need_resched; }
And cond_resched() repeat this loop:
do { add_preempt_count(PREEMPT_ACTIVE); schedule(); sub_preempt_count(PREEMPT_ACTIVE); } while(need_resched());
This loop is needless because schedule() already did the check and nothing can set TIF_NEED_RESCHED between schedule() exit and the loop check in need_resched().
Then remove this needless loop.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1247725694-6082-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
--- kernel/sched.c | 8 +++----- 1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c index 03f7e3f..4c5ee84 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -6618,11 +6618,9 @@ static void __cond_resched(void) * PREEMPT_ACTIVE, which could trigger a second * cond_resched() call. */ - do { - add_preempt_count(PREEMPT_ACTIVE); - schedule(); - sub_preempt_count(PREEMPT_ACTIVE); - } while (need_resched()); + add_preempt_count(PREEMPT_ACTIVE); + schedule(); + sub_preempt_count(PREEMPT_ACTIVE); } int __sched _cond_resched(void)
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