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| author | Paul Turner <pjt@google.com> | 2011-07-05 19:07:21 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2011-07-21 18:01:43 +0200 |
| commit | 9bbd7374361d9bfc75108c3ad1c1b6db28b1be59 (patch) | |
| tree | d787a387a2a2e3d8c0476b79ae57dd217098763f /kernel/sched_fair.c | |
| parent | 994bf1c92270e3d7731ea08f1d1bd7a668314e60 (diff) | |
| download | lwn-9bbd7374361d9bfc75108c3ad1c1b6db28b1be59.tar.gz lwn-9bbd7374361d9bfc75108c3ad1c1b6db28b1be59.zip | |
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>
Diffstat (limited to 'kernel/sched_fair.c')
| -rw-r--r-- | kernel/sched_fair.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index e7d67a9e259a..f88720b3df8b 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) { /* |