Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754580AbdCFOcK (ORCPT ); Mon, 6 Mar 2017 09:32:10 -0500 Received: from mail.kernel.org ([198.145.29.136]:50436 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754403AbdCFOaH (ORCPT ); Mon, 6 Mar 2017 09:30:07 -0500 Date: Mon, 6 Mar 2017 09:29:59 -0500 From: Steven Rostedt To: Viresh Kumar Cc: Patrick Bellasi , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Vincent Guittot , John Stultz , Juri Lelli , Todd Kjos , Tim Murray , Andres Oportus , Joel Fernandes , Morten Rasmussen , Dietmar Eggemann , Chris Redpath , Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" Subject: Re: [PATCH 1/6] cpufreq: schedutil: reset sg_cpus's flags at IDLE enter Message-ID: <20170306092959.561fdf26@gandalf.local.home> In-Reply-To: <20170303034125.GH13760@vireshk-i7> References: <1488469507-32463-1-git-send-email-patrick.bellasi@arm.com> <1488469507-32463-2-git-send-email-patrick.bellasi@arm.com> <20170303034125.GH13760@vireshk-i7> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2527 Lines: 80 On Fri, 3 Mar 2017 09:11:25 +0530 Viresh Kumar wrote: > On 02-03-17, 15:45, Patrick Bellasi wrote: > > diff --git a/include/linux/sched.h b/include/linux/sched.h > > index e2ed46d..739b29d 100644 > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -3653,6 +3653,7 @@ static inline unsigned long rlimit_max(unsigned int limit) > > #define SCHED_CPUFREQ_RT (1U << 0) > > #define SCHED_CPUFREQ_DL (1U << 1) > > #define SCHED_CPUFREQ_IOWAIT (1U << 2) > > +#define SCHED_CPUFREQ_IDLE (1U << 3) > > > > #define SCHED_CPUFREQ_RT_DL (SCHED_CPUFREQ_RT | SCHED_CPUFREQ_DL) > > > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > > index fd46593..084a98b 100644 > > --- a/kernel/sched/cpufreq_schedutil.c > > +++ b/kernel/sched/cpufreq_schedutil.c > > @@ -281,6 +281,12 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, > > > > raw_spin_lock(&sg_policy->update_lock); > > > > + /* CPU is entering IDLE, reset flags without triggering an update */ > > + if (flags & SCHED_CPUFREQ_IDLE) { > > Will "flags == SCHED_CPUFREQ_IDLE" generate better assembly ? > Even if it does, a bit check and an equal check are pretty negligible in difference wrt execution time. I would choose whatever is the most readable to humans. flags == SCHED_CPUFREQ_IDLE will tell me (as a reviewer) that we expect no other flag to be set. flags & SCHED_CPUFREQ_IDLE will tell me that we only care about the IDLE flag. Which ever is the more meaningful is what should be used. -- Steve > > + sg_cpu->flags = 0; > > + goto done; > > + } > > + > > sg_cpu->util = util; > > sg_cpu->max = max; > > sg_cpu->flags = flags; > > @@ -293,6 +299,7 @@ static void sugov_update_shared(struct update_util_data *hook, u64 time, > > sugov_update_commit(sg_policy, time, next_f); > > } > > > > +done: > > raw_spin_unlock(&sg_policy->update_lock); > > } > > > > diff --git a/kernel/sched/idle_task.c b/kernel/sched/idle_task.c > > index 0c00172..a844c91 100644 > > --- a/kernel/sched/idle_task.c > > +++ b/kernel/sched/idle_task.c > > @@ -29,6 +29,10 @@ pick_next_task_idle(struct rq *rq, struct task_struct *prev, struct rq_flags *rf > > put_prev_task(rq, prev); > > update_idle_core(rq); > > schedstat_inc(rq->sched_goidle); > > + > > + /* kick cpufreq (see the comment in kernel/sched/sched.h). */ > > + cpufreq_update_this_cpu(rq, SCHED_CPUFREQ_IDLE); > > + > > return rq->idle; > > } > > > > -- > > 2.7.4 >