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 <pjt@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/CAPM31R+2Ke2urUZKao5W92_LupdR4AYEv-EZWiJ3tG=tEes2cw@mail.gmail.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -1919,8 +1919,8 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
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if (!sched_feat(WAKEUP_PREEMPT))
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if (!sched_feat(WAKEUP_PREEMPT))
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return;
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return;
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update_curr(cfs_rq);
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find_matching_se(&se, &pse);
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find_matching_se(&se, &pse);
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update_curr(cfs_rq_of(se));
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BUG_ON(!pse);
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BUG_ON(!pse);
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if (wakeup_preempt_entity(se, pse) == 1) {
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if (wakeup_preempt_entity(se, pse) == 1) {
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/*
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/*
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