From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9AFEBC282C3 for ; Tue, 22 Jan 2019 10:38:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61B1C217F5 for ; Tue, 22 Jan 2019 10:38:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727791AbfAVKin (ORCPT ); Tue, 22 Jan 2019 05:38:43 -0500 Received: from cloudserver094114.home.pl ([79.96.170.134]:48341 "EHLO cloudserver094114.home.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726530AbfAVKim (ORCPT ); Tue, 22 Jan 2019 05:38:42 -0500 Received: from 79.184.255.239.ipv4.supernova.orange.pl (79.184.255.239) (HELO aspire.rjw.lan) by serwer1319399.home.pl (79.96.170.134) with SMTP (IdeaSmtpServer 0.83.183) id 7c665964e6219056; Tue, 22 Jan 2019 11:38:39 +0100 From: "Rafael J. Wysocki" To: Patrick Bellasi Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-api@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Tejun Heo , "Rafael J . Wysocki" , Vincent Guittot , Viresh Kumar , Paul Turner , Quentin Perret , Dietmar Eggemann , Morten Rasmussen , Juri Lelli , Todd Kjos , Joel Fernandes , Steve Muckle , Suren Baghdasaryan Subject: Re: [PATCH v6 08/16] sched/cpufreq: uclamp: Add utilization clamping for FAIR tasks Date: Tue, 22 Jan 2019 11:37:42 +0100 Message-ID: <3006911.57lVBuUGX3@aspire.rjw.lan> In-Reply-To: <20190115101513.2822-9-patrick.bellasi@arm.com> References: <20190115101513.2822-1-patrick.bellasi@arm.com> <20190115101513.2822-9-patrick.bellasi@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, January 15, 2019 11:15:05 AM CET Patrick Bellasi wrote: > Each time a frequency update is required via schedutil, a frequency is > selected to (possibly) satisfy the utilization reported by each > scheduling class. However, when utilization clamping is in use, the > frequency selection should consider userspace utilization clamping > hints. This will allow, for example, to: > > - boost tasks which are directly affecting the user experience > by running them at least at a minimum "requested" frequency > > - cap low priority tasks not directly affecting the user experience > by running them only up to a maximum "allowed" frequency > > These constraints are meant to support a per-task based tuning of the > frequency selection thus supporting a fine grained definition of > performance boosting vs energy saving strategies in kernel space. > > Add support to clamp the utilization and IOWait boost of RUNNABLE FAIR > tasks within the boundaries defined by their aggregated utilization > clamp constraints. > Based on the max(min_util, max_util) of each task, max-aggregated the > CPU clamp value in a way to give the boosted tasks the performance they > need when they happen to be co-scheduled with other capped tasks. > > Signed-off-by: Patrick Bellasi > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: Rafael J. Wysocki > > --- > Changes in v6: > Message-ID: <20181107113849.GC14309@e110439-lin> > - sanity check util_max >= util_min > Others: > - wholesale s/group/bucket/ > - wholesale s/_{get,put}/_{inc,dec}/ to match refcount APIs > --- > kernel/sched/cpufreq_schedutil.c | 27 ++++++++++++++++++++++++--- > kernel/sched/sched.h | 23 +++++++++++++++++++++++ > 2 files changed, 47 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c > index 033ec7c45f13..520ee2b785e7 100644 > --- a/kernel/sched/cpufreq_schedutil.c > +++ b/kernel/sched/cpufreq_schedutil.c > @@ -218,8 +218,15 @@ unsigned long schedutil_freq_util(int cpu, unsigned long util_cfs, > * CFS tasks and we use the same metric to track the effective > * utilization (PELT windows are synchronized) we can directly add them > * to obtain the CPU's actual utilization. > + * > + * CFS utilization can be boosted or capped, depending on utilization > + * clamp constraints requested by currently RUNNABLE tasks. > + * When there are no CFS RUNNABLE tasks, clamps are released and > + * frequency will be gracefully reduced with the utilization decay. > */ > - util = util_cfs; > + util = (type == ENERGY_UTIL) > + ? util_cfs > + : uclamp_util(rq, util_cfs); > util += cpu_util_rt(rq); > > dl_util = cpu_util_dl(rq); > @@ -327,6 +334,7 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, > unsigned int flags) > { > bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT; > + unsigned int max_boost; > > /* Reset boost if the CPU appears to have been idle enough */ > if (sg_cpu->iowait_boost && > @@ -342,11 +350,24 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, > return; > sg_cpu->iowait_boost_pending = true; > > + /* > + * Boost FAIR tasks only up to the CPU clamped utilization. > + * > + * Since DL tasks have a much more advanced bandwidth control, it's > + * safe to assume that IO boost does not apply to those tasks. > + * Instead, since RT tasks are not utilization clamped, we don't want > + * to apply clamping on IO boost while there is blocked RT > + * utilization. > + */ > + max_boost = sg_cpu->iowait_boost_max; > + if (!cpu_util_rt(cpu_rq(sg_cpu->cpu))) > + max_boost = uclamp_util(cpu_rq(sg_cpu->cpu), max_boost); > + > /* Double the boost at each request */ > if (sg_cpu->iowait_boost) { > sg_cpu->iowait_boost <<= 1; > - if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max) > - sg_cpu->iowait_boost = sg_cpu->iowait_boost_max; > + if (sg_cpu->iowait_boost > max_boost) > + sg_cpu->iowait_boost = max_boost; > return; > } > > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index b7f3ee8ba164..95d62a2a0b44 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -2267,6 +2267,29 @@ static inline unsigned int uclamp_none(int clamp_id) > return SCHED_CAPACITY_SCALE; > } > > +#ifdef CONFIG_UCLAMP_TASK > +static inline unsigned int uclamp_util(struct rq *rq, unsigned int util) > +{ > + unsigned int min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); > + unsigned int max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); > + > + /* > + * Since CPU's {min,max}_util clamps are MAX aggregated considering > + * RUNNABLE tasks with _different_ clamps, we can end up with an > + * invertion, which we can fix at usage time. > + */ > + if (unlikely(min_util >= max_util)) > + return min_util; > + > + return clamp(util, min_util, max_util); > +} > +#else /* CONFIG_UCLAMP_TASK */ > +static inline unsigned int uclamp_util(struct rq *rq, unsigned int util) > +{ > + return util; > +} > +#endif /* CONFIG_UCLAMP_TASK */ > + > #ifdef arch_scale_freq_capacity > # ifndef arch_scale_freq_invariant > # define arch_scale_freq_invariant() true > IMO it would be better to combine this patch with the next one. At least some things in it I was about to ask about would go away then. :-) Besides, I don't really see a reason for the split here.