From: Kirill Tkhai Date: Wed, 30 Jan 2013 12:50:36 +0000 (+0400) Subject: sched/rt: Do not account zero delta_exec in update_curr_rt() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=fc79e240be5aa379dd36a62158be5a5ee0e4aec7;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git sched/rt: Do not account zero delta_exec in update_curr_rt() There are several places of consecutive calls of dequeue_task_rt() and put_prev_task_rt() in the scheduler. For example, function rt_mutex_setprio() does it. The both calls lead to update_curr_rt(), the second of it receives zeroed delta_exec. The only effective action in this case is call of sched_rt_avg_update(), which can change rq->age_stamp and rq->rt_avg. But it is possible in case of ""floating"" rq->clock. This fact is not reasonable to be accounted. Another actions do nothing. Signed-off-by: Kirill V Tkhai Acked-by: Steven Rostedt Cc: Peter Zijlstra CC: linux-rt-users Link: http://lkml.kernel.org/r/931541359550236@web1g.yandex.ru Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 2f69ca997826..94abca4d9cf5 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -925,8 +925,8 @@ static void update_curr_rt(struct rq *rq) return; delta_exec = rq->clock_task - curr->se.exec_start; - if (unlikely((s64)delta_exec < 0)) - delta_exec = 0; + if (unlikely((s64)delta_exec <= 0)) + return; schedstat_set(curr->se.statistics.exec_max, max(curr->se.statistics.exec_max, delta_exec));