From mboxrd@z Thu Jan 1 00:00:00 1970 From: tip-bot for Kirill Tkhai Subject: [tip:sched/core] sched/rt: Do not account zero delta_exec in update_curr_rt() Date: Thu, 31 Jan 2013 03:06:09 -0800 Message-ID: References: <931541359550236@web1g.yandex.ru> Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, rostedt@goodmis.org, peterz@infradead.org, tkhai@yandex.ru, tglx@linutronix.de, linux-rt-users@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, linux-rt-users@vger.kernel.org, rostedt@goodmis.org, tkhai@yandex.ru, tglx@linutronix.de To: linux-tip-commits@vger.kernel.org Return-path: Received: from terminus.zytor.com ([198.137.202.10]:36405 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751651Ab3AaLG1 (ORCPT ); Thu, 31 Jan 2013 06:06:27 -0500 In-Reply-To: <931541359550236@web1g.yandex.ru> Content-Disposition: inline Sender: linux-rt-users-owner@vger.kernel.org List-ID: Commit-ID: fc79e240be5aa379dd36a62158be5a5ee0e4aec7 Gitweb: http://git.kernel.org/tip/fc79e240be5aa379dd36a62158be5a5ee0e4aec7 Author: Kirill Tkhai AuthorDate: Wed, 30 Jan 2013 16:50:36 +0400 Committer: Ingo Molnar CommitDate: Thu, 31 Jan 2013 10:31:13 +0100 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 --- kernel/sched/rt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 2f69ca9..94abca4 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));