Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752534AbcDVMFK (ORCPT ); Fri, 22 Apr 2016 08:05:10 -0400 Received: from mga03.intel.com ([134.134.136.65]:37011 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751718AbcDVMFI (ORCPT ); Fri, 22 Apr 2016 08:05:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,517,1455004800"; d="scan'208";a="937969418" Subject: Re: [PATCH v3] sched/cpufreq: optimize cpufreq update kicker to avoid update multiple times To: Wanpeng Li , Peter Zijlstra References: <1461316044-9520-1-git-send-email-wanpeng.li@hotmail.com> Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Wanpeng Li , Linux PM From: "Rafael J. Wysocki" Organization: Intel Technology Poland Sp. z o. o., KRS 101882, ul. Slowackiego 173, 80-298 Gdansk Message-ID: <571A1368.9060409@intel.com> Date: Fri, 22 Apr 2016 14:04:56 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <1461316044-9520-1-git-send-email-wanpeng.li@hotmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2683 Lines: 81 [Added linux-pm to the CC - can you please do so for PM-related patches in the future?] On 4/22/2016 11:07 AM, Wanpeng Li wrote: > From: Wanpeng Li > > Sometimes delta_exec is 0 due to update_curr() is called multiple times, > this is captured by: > > u64 delta_exec = rq_clock_task(rq) - curr->se.exec_start; > > This patch optimizes the cpufreq update kicker by bailing out when nothing > changed, it will benefit the upcoming schedutil, since otherwise it will > (over)react to the special util/max combination. > > Signed-off-by: Wanpeng Li The changelog looks better now, thanks! Peter, do I think correctly that you're going to take care of this one? Or do you want me to take it? > --- > v1 -> v2: > * add From: head > v2 -> v3: > * update changelog > > kernel/sched/deadline.c | 8 ++++---- > kernel/sched/rt.c | 8 ++++---- > 2 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c > index affd97e..8f9b5af 100644 > --- a/kernel/sched/deadline.c > +++ b/kernel/sched/deadline.c > @@ -717,10 +717,6 @@ static void update_curr_dl(struct rq *rq) > if (!dl_task(curr) || !on_dl_rq(dl_se)) > return; > > - /* Kick cpufreq (see the comment in linux/cpufreq.h). */ > - if (cpu_of(rq) == smp_processor_id()) > - cpufreq_trigger_update(rq_clock(rq)); > - > /* > * Consumed budget is computed considering the time as > * observed by schedulable tasks (excluding time spent > @@ -736,6 +732,10 @@ static void update_curr_dl(struct rq *rq) > return; > } > > + /* kick cpufreq (see the comment in linux/cpufreq.h). */ > + if (cpu_of(rq) == smp_processor_id()) > + cpufreq_trigger_update(rq_clock(rq)); > + > schedstat_set(curr->se.statistics.exec_max, > max(curr->se.statistics.exec_max, delta_exec)); > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c > index c41ea7a..19e1306 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -953,14 +953,14 @@ static void update_curr_rt(struct rq *rq) > if (curr->sched_class != &rt_sched_class) > return; > > - /* Kick cpufreq (see the comment in linux/cpufreq.h). */ > - if (cpu_of(rq) == smp_processor_id()) > - cpufreq_trigger_update(rq_clock(rq)); > - > delta_exec = rq_clock_task(rq) - curr->se.exec_start; > if (unlikely((s64)delta_exec <= 0)) > return; > > + /* Kick cpufreq (see the comment in linux/cpufreq.h). */ > + if (cpu_of(rq) == smp_processor_id()) > + cpufreq_trigger_update(rq_clock(rq)); > + > schedstat_set(curr->se.statistics.exec_max, > max(curr->se.statistics.exec_max, delta_exec)); >