Re: [PATCH]sched/rt: Do not account zero delta_exec in update_curr_rt()
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2013-01-30 13:35:21
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On Wed, 2013-01-30 at 16:50 +0400, Kirill Tkhai wrote:
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 <redacted>
Acked-by: Steven Rostedt <rostedt@goodmis.org> -- Steve
quoted hunk ↗ jump to hunk
CC: Ingo Molnar <mingo@kernel.org> CC: Peter Zijlstra <peterz@infradead.org> CC: linux-rt-users <redacted> --- kernel/sched/rt.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 4e8f0f4..c6d7993 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));