From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755768AbbIYJIL (ORCPT ); Fri, 25 Sep 2015 05:08:11 -0400 Received: from LGEAMRELO12.lge.com ([156.147.23.52]:45971 "EHLO lgeamrelo12.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755728AbbIYJII (ORCPT ); Fri, 25 Sep 2015 05:08:08 -0400 X-Greylist: delayed 900 seconds by postgrey-1.27 at vger.kernel.org; Fri, 25 Sep 2015 05:08:07 EDT X-Original-SENDERIP: 156.147.1.121 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 165.244.98.76 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com From: To: mingo@kernel.org, peterz@infradead.org CC: linux-kernel@vger.kernel.org, fweisbec@gmail.com, tglx@linutronix.de, Byungchul Park Subject: [RESEND PATCH] sched: consider missed ticks when updating global cpu load Date: Fri, 25 Sep 2015 17:52:37 +0900 Message-ID: <1443171157-23384-1-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.7.9.5 X-MIMETrack: Itemize by SMTP Server on LGEKRMHUB07/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2015/09/25 17:53:06, Serialize by Router on LGEKRMHUB07/LGE/LG Group(Release 8.5.3FP6|November 21, 2013) at 2015/09/25 17:53:06, Serialize complete at 2015/09/25 17:53:06 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Byungchul Park hello, i have already sent this patch about 1 month ago. (see https://lkml.org/lkml/2015/8/13/160) now, i am resending the same patch with adding some additional commit message. thank you, byungchul ----->8----- >>From 8ece9a0482e74a39cd2e9165bf8eec1d04665fa9 Mon Sep 17 00:00:00 2001 From: Byungchul Park Date: Fri, 25 Sep 2015 17:10:10 +0900 Subject: [RESEND PATCH] sched: consider missed ticks when updating global cpu load in hrtimer_interrupt(), the first tick_program_event() can be failed because the next timer could be already expired due to, (see the comment in hrtimer_interrupt()) - tracing - long lasting callbacks - being scheduled away when running in a VM in the case that the first tick_program_event() is failed, the second tick_program_event() set the expired time to more than one tick later. then next tick can happen after more than one tick, even though tick is not stopped by e.g. NOHZ. when the next tick occurs, update_process_times() -> scheduler_tick() -> update_cpu_load_active() is performed, assuming the distance between last tick and current tick is 1 tick! it's wrong in this case. thus, this abnormal case should be considered in update_cpu_load_active(). Signed-off-by: Byungchul Park --- kernel/sched/fair.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 4d5f97b..829282f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4356,12 +4356,15 @@ void update_cpu_load_nohz(void) */ void update_cpu_load_active(struct rq *this_rq) { + unsigned long curr_jiffies = READ_ONCE(jiffies); + unsigned long pending_updates; unsigned long load = weighted_cpuload(cpu_of(this_rq)); /* * See the mess around update_idle_cpu_load() / update_cpu_load_nohz(). */ - this_rq->last_load_update_tick = jiffies; - __update_cpu_load(this_rq, load, 1); + pending_updates = curr_jiffies - this_rq->last_load_update_tick; + this_rq->last_load_update_tick = curr_jiffies; + __update_cpu_load(this_rq, load, pending_updates); } /* -- 1.7.9.5