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Message-Id: <20121001225159.013913784@1wt.eu> Date: Tue, 02 Oct 2012 00:52:30 +0200 From: Willy Tarreau <w@....eu> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Mike Galbraith <efault@....de>, Peter Zijlstra <a.p.zijlstra@...llo.nl>, Ingo Molnar <mingo@...e.hu>, Willy Tarreau <w@....eu> Subject: [ 033/180] sched: Fix signed unsigned comparison in check_preempt_tick() 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Mike Galbraith <efault@....de> commit d7d8294415f0ce4254827d4a2a5ee88b00be52a8 upstream. Signed unsigned comparison may lead to superfluous resched if leftmost is right of the current task, wasting a few cycles, and inadvertently _lengthening_ the current task's slice. Reported-by: Venkatesh Pallipadi <venki@...gle.com> Signed-off-by: Mike Galbraith <efault@....de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> LKML-Reference: <1294202477.9384.5.camel@...ge.simson.net> Signed-off-by: Ingo Molnar <mingo@...e.hu> Signed-off-by: Willy Tarreau <w@....eu> --- kernel/sched_fair.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index cd9a40b..fd6e5f2 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -862,6 +862,9 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) struct sched_entity *se = __pick_next_entity(cfs_rq); s64 delta = curr->vruntime - se->vruntime; + if (delta < 0) + return; + if (delta > ideal_runtime) resched_task(rq_of(cfs_rq)->curr); } -- 1.7.2.1.45.g54fbc -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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