From: Paul Turner Date: Wed, 6 Jul 2011 02:07:21 +0000 (-0700) Subject: sched: update correct entity's runtime in check_preempt_wakeup() X-Git-Tag: upstream/snapshot3+hdmi~9606^2~9 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=9bbd7374361d9bfc75108c3ad1c1b6db28b1be59;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git sched: update correct entity's runtime in check_preempt_wakeup() While looking at check_preempt_wakeup() I realized that we are potentially updating the wrong entity in the fair-group scheduling case. In this case the current task's cfs_rq may not be the same as the one used for the comparison between the waking task and the existing task's vruntime. This potentially results in us using a stale vruntime in the pre-emption decision, providing a small false preference for the previous task. The effects of this are bounded since we always perform a hierarchal update on the tick. Signed-off-by: Paul Turner Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/CAPM31R+2Ke2urUZKao5W92_LupdR4AYEv-EZWiJ3tG=tEes2cw@mail.gmail.com Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index e7d67a9..f88720b 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1919,8 +1919,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ if (!sched_feat(WAKEUP_PREEMPT)) return; - update_curr(cfs_rq); find_matching_se(&se, &pse); + update_curr(cfs_rq_of(se)); BUG_ON(!pse); if (wakeup_preempt_entity(se, pse) == 1) { /*