From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753687Ab3A3Mup (ORCPT ); Wed, 30 Jan 2013 07:50:45 -0500 Received: from forward19.mail.yandex.net ([95.108.253.144]:44933 "EHLO forward19.mail.yandex.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751851Ab3A3Mul (ORCPT ); Wed, 30 Jan 2013 07:50:41 -0500 From: Kirill Tkhai To: "linux-kernel@vger.kernel.org" Cc: Steven Rostedt , Ingo Molnar , Peter Zijlstra , linux-rt-users Subject: [PATCH]sched/rt: Do not account zero delta_exec in update_curr_rt() MIME-Version: 1.0 Message-Id: <931541359550236@web1g.yandex.ru> X-Mailer: Yamail [ http://yandex.ru ] 5.0 Date: Wed, 30 Jan 2013 16:50:36 +0400 Content-Transfer-Encoding: 7bit Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 CC: Steven Rostedt CC: Ingo Molnar CC: Peter Zijlstra CC: linux-rt-users --- 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));