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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D495C433EF for ; Thu, 21 Jul 2022 14:25:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232123AbiGUOZ0 (ORCPT ); Thu, 21 Jul 2022 10:25:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35748 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232106AbiGUOY6 (ORCPT ); Thu, 21 Jul 2022 10:24:58 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8710882FB4 for ; Thu, 21 Jul 2022 07:24:50 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C9C671042; Thu, 21 Jul 2022 07:24:50 -0700 (PDT) Received: from wubuntu (unknown [10.57.86.173]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0CFFF3F73D; Thu, 21 Jul 2022 07:24:48 -0700 (PDT) Date: Thu, 21 Jul 2022 15:24:47 +0100 From: Qais Yousef To: Xuewen Yan Cc: Ingo Molnar , "Peter Zijlstra (Intel)" , Vincent Guittot , Dietmar Eggemann , linux-kernel@vger.kernel.org, Wei Wang , Jonathan JMChen , Hank Subject: Re: [PATCH 7/7] sched/uclamp: Cater for uclamp in find_energy_efficient_cpu()'s early exit condition Message-ID: <20220721142447.emsv6q3y4ch3bphi@wubuntu> References: <20220629194632.1117723-1-qais.yousef@arm.com> <20220629194632.1117723-8-qais.yousef@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/20/22 15:39, Xuewen Yan wrote: > Hi Qais > > On Thu, Jun 30, 2022 at 3:48 AM Qais Yousef wrote: > > > > If the utilization of the woken up task is 0, we skip the energy > > calculation because it has no impact. > > > > But if the task is boosted (uclamp_min != 0) will have an impact on task > > placement and frequency selection. Only skip if the util is truly > > 0 after applying uclamp values. > > > > Change uclamp_task_cpu() signature to avoid unnecessary additional calls > > to uclamp_eff_get(). feec() is the only user now. > > > > Fixes: 732cd75b8c920 ("sched/fair: Select an energy-efficient CPU on task wake-up") > > Signed-off-by: Qais Yousef > > --- > > kernel/sched/fair.c | 14 ++++++++------ > > 1 file changed, 8 insertions(+), 6 deletions(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 499ef7a7288c..a112ca45864c 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -4057,14 +4057,16 @@ static inline unsigned long task_util_est(struct task_struct *p) > > } > > > > #ifdef CONFIG_UCLAMP_TASK > > -static inline unsigned long uclamp_task_util(struct task_struct *p) > > +static inline unsigned long uclamp_task_util(struct task_struct *p, > > + unsigned long uclamp_min, > > + unsigned long uclamp_max) > > { > > - return clamp(task_util_est(p), > > - uclamp_eff_value(p, UCLAMP_MIN), > > - uclamp_eff_value(p, UCLAMP_MAX)); > > + return clamp(task_util_est(p), uclamp_min, uclamp_max); > > } > > #else > > -static inline unsigned long uclamp_task_util(struct task_struct *p) > > +static inline unsigned long uclamp_task_util(struct task_struct *p, > > + unsigned long uclamp_min, > > + unsigned long uclamp_max) > > { > > return task_util_est(p); > > } > > @@ -6913,7 +6915,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) > > target = prev_cpu; > > > > sync_entity_load_avg(&p->se); > > - if (!task_util_est(p)) > > + if (!uclamp_task_util(p, p_util_min, p_util_max)) > > Is it not enough to just replace the task_util_est with the > uclamp_task_util? If change the definition of uclamp_task_util, > that means it have to get task's uclamp first if user want to call the > function, may increase the code complex farther more? Calling uclamp_eff_value() all the time is not cheap actually. We can easily add two versions when we need to: __uclamp_task_util(p, uclamp_min, uclamp_max); uclamp_task_util(p) { uclamp_min = uclamp_eff_value(); uclamp_max = uclamp_eff_value(); return __uclamp_eff_value(p, uclamp_min, uclamp_max); } When we need to. Since we have a single user now, there's no need to do this now and if we ever get more users it'd be easy to refactor then? Thanks! -- Qais Yousef > > > goto unlock; > > > > for (; pd; pd = pd->next) { > > -- > > 2.25.1 > > > > BR > --- > xuewen.yan