From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752014AbeEQNL6 (ORCPT ); Thu, 17 May 2018 09:11:58 -0400 Received: from mail-pg0-f66.google.com ([74.125.83.66]:38041 "EHLO mail-pg0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbeEQNL5 (ORCPT ); Thu, 17 May 2018 09:11:57 -0400 X-Google-Smtp-Source: AB8JxZrbjvDoW2xGrJEgya9vW3BVFP1GRo9maHVLeovwKbmRKV2VRS/3gzj3dV5Y0OPvNdEBKjuenQ== Date: Thu, 17 May 2018 06:11:55 -0700 From: Joel Fernandes To: Viresh Kumar Cc: linux-kernel@vger.kernel.org, "Rafael J . Wysocki" , Peter Zijlstra , Ingo Molnar , Patrick Bellasi , Juri Lelli , Luca Abeni , kernel-team@android.com, linux-pm@vger.kernel.org Subject: Re: [PATCH RFC] schedutil: Allow cpufreq requests to be made even when kthread kicked Message-ID: <20180517131155.GB139147@joelaf.mtv.corp.google.com> References: <20180516224518.109891-1-joel@joelfernandes.org> <20180517050611.yj2alkzckl3ximzu@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180517050611.yj2alkzckl3ximzu@vireshk-i7> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 17, 2018 at 10:36:11AM +0530, Viresh Kumar wrote: > On 16-05-18, 15:45, Joel Fernandes (Google) wrote: > > kernel/sched/cpufreq_schedutil.c | 36 +++++++++++++++++++++++++------- > > 1 file changed, 28 insertions(+), 8 deletions(-) > > > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > > index e13df951aca7..a87fc281893d 100644 > > --- a/kernel/sched/cpufreq_schedutil.c > > +++ b/kernel/sched/cpufreq_schedutil.c > > @@ -92,9 +92,6 @@ static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time) > > !cpufreq_can_do_remote_dvfs(sg_policy->policy)) > > return false; > > > > - if (sg_policy->work_in_progress) > > - return false; > > - > > if (unlikely(sg_policy->need_freq_update)) { > > sg_policy->need_freq_update = false; > > /* > > @@ -129,8 +126,11 @@ static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time, > > policy->cur = next_freq; > > trace_cpu_frequency(next_freq, smp_processor_id()); > > } else { > > - sg_policy->work_in_progress = true; > > - irq_work_queue(&sg_policy->irq_work); > > + /* Don't queue request if one was already queued */ > > + if (!sg_policy->work_in_progress) { > > Merge it above to make it "else if". Sure. > > + sg_policy->work_in_progress = true; > > + irq_work_queue(&sg_policy->irq_work); > > + } > > } > > } > > > > @@ -291,6 +291,15 @@ static void sugov_update_single(struct update_util_data *hook, u64 time, > > > > ignore_dl_rate_limit(sg_cpu, sg_policy); > > > > + /* > > + * For slow-switch systems, single policy requests can't run at the > > + * moment if the governor thread is already processing a pending > > + * frequency switch request, this can be fixed by acquiring update_lock > > + * while updating next_freq and work_in_progress but we prefer not to. > > + */ > > + if (sg_policy->work_in_progress) > > + return; > > + > > @Rafael: Do you think its worth start using the lock now for unshared > policies ? Will wait for confirmation before next revision. > > if (!sugov_should_update_freq(sg_policy, time)) > > return; > > > > @@ -382,13 +391,24 @@ sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags) > > static void sugov_work(struct kthread_work *work) > > { > > struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work); > > + unsigned int freq; > > + unsigned long flags; > > + > > + /* > > + * Hold sg_policy->update_lock shortly to handle the case where: > > + * incase sg_policy->next_freq is read here, and then updated by > > + * sugov_update_shared just before work_in_progress is set to false > > + * here, we may miss queueing the new update. > > + */ > > + raw_spin_lock_irqsave(&sg_policy->update_lock, flags); > > + freq = sg_policy->next_freq; > > + sg_policy->work_in_progress = false; > > + raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags); > > > > mutex_lock(&sg_policy->work_lock); > > - __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq, > > + __cpufreq_driver_target(sg_policy->policy, freq, > > CPUFREQ_RELATION_L); > > No need of line break anymore. Yes, will fix. > > mutex_unlock(&sg_policy->work_lock); > > - > > - sg_policy->work_in_progress = false; > > } > > > > static void sugov_irq_work(struct irq_work *irq_work) > > LGTM. Cool, thanks. - Joel