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Date: Wed, 30 Jan 2013 08:35:16 -0500 From: Steven Rostedt <rostedt@...dmis.org> To: Kirill Tkhai <tkhai@...dex.ru> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>, Peter Zijlstra <peterz@...radead.org>, linux-rt-users <linux-rt-users@...r.kernel.org> Subject: Re: [PATCH]sched/rt: Do not account zero delta_exec in update_curr_rt() 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 <tkhai@...dex.ru> Acked-by: Steven Rostedt <rostedt@...dmis.org> -- Steve > CC: Ingo Molnar <mingo@...nel.org> > CC: Peter Zijlstra <peterz@...radead.org> > CC: linux-rt-users <linux-rt-users@...r.kernel.org> > --- > 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)); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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