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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 965AEC282DE for ; Wed, 5 Jun 2019 09:16:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 780FE2075B for ; Wed, 5 Jun 2019 09:16:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727012AbfFEJQx (ORCPT ); Wed, 5 Jun 2019 05:16:53 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:56122 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726502AbfFEJQx (ORCPT ); Wed, 5 Jun 2019 05:16:53 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 940A5A78; Wed, 5 Jun 2019 02:16:52 -0700 (PDT) Received: from queper01-lin (queper01-lin.cambridge.arm.com [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 800803F690; Wed, 5 Jun 2019 02:16:51 -0700 (PDT) Date: Wed, 5 Jun 2019 10:16:46 +0100 From: Quentin Perret To: Viresh Kumar Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, Vincent Guittot Subject: Re: [PATCH] sched/fair: Introduce fits_capacity() Message-ID: <20190605091644.w3g7hc7r3eiscz4f@queper01-lin> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Viresh, On Tuesday 04 Jun 2019 at 12:31:52 (+0530), Viresh Kumar wrote: > The same formula to check utilization against capacity (after > considering capacity_margin) is already used at 5 different locations. > > This patch creates a new macro, fits_capacity(), which can be used from > all these locations without exposing the details of it and hence > simplify code. > > All the 5 code locations are updated as well to use it.. > > Signed-off-by: Viresh Kumar > --- > kernel/sched/fair.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 7f8d477f90fe..db3a218b7928 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -102,6 +102,8 @@ int __weak arch_asym_cpu_priority(int cpu) > * (default: ~20%) > */ > static unsigned int capacity_margin = 1280; > + > +#define fits_capacity(cap, max) ((cap) * capacity_margin < (max) * 1024) > #endif > > #ifdef CONFIG_CFS_BANDWIDTH > @@ -3727,7 +3729,7 @@ util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep) > > static inline int task_fits_capacity(struct task_struct *p, long capacity) > { > - return capacity * 1024 > task_util_est(p) * capacity_margin; > + return fits_capacity(task_util_est(p), capacity); > } > > static inline void update_misfit_status(struct task_struct *p, struct rq *rq) > @@ -5143,7 +5145,7 @@ static inline unsigned long cpu_util(int cpu); > > static inline bool cpu_overutilized(int cpu) > { > - return (capacity_of(cpu) * 1024) < (cpu_util(cpu) * capacity_margin); > + return !fits_capacity(cpu_util(cpu), capacity_of(cpu)); This ... > } > > static inline void update_overutilized_status(struct rq *rq) > @@ -6304,7 +6306,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) > /* Skip CPUs that will be overutilized. */ > util = cpu_util_next(cpu, p, cpu); > cpu_cap = capacity_of(cpu); > - if (cpu_cap * 1024 < util * capacity_margin) > + if (!fits_capacity(util, cpu_cap)) ... and this isn't _strictly_ equivalent to the existing code but I guess we can live with the difference :-) > continue; > > /* Always use prev_cpu as a candidate. */ > @@ -7853,8 +7855,7 @@ group_is_overloaded(struct lb_env *env, struct sg_lb_stats *sgs) > static inline bool > group_smaller_min_cpu_capacity(struct sched_group *sg, struct sched_group *ref) > { > - return sg->sgc->min_capacity * capacity_margin < > - ref->sgc->min_capacity * 1024; > + return fits_capacity(sg->sgc->min_capacity, ref->sgc->min_capacity); > } > > /* > @@ -7864,8 +7865,7 @@ group_smaller_min_cpu_capacity(struct sched_group *sg, struct sched_group *ref) > static inline bool > group_smaller_max_cpu_capacity(struct sched_group *sg, struct sched_group *ref) > { > - return sg->sgc->max_capacity * capacity_margin < > - ref->sgc->max_capacity * 1024; > + return fits_capacity(sg->sgc->max_capacity, ref->sgc->max_capacity); > } > > static inline enum > -- > 2.21.0.rc0.269.g1a574e7a288b > Also, since we're talking about making the capacity_margin code more consistent, one small thing I had in mind: we have a capacity margin in sugov too, which happens to be 1.25 has well (see map_util_freq()). Conceptually, capacity_margin in fair.c and the sugov margin are both about answering: "do I have enough CPU capacity to serve X of util, or do I need more ?" So perhaps we should factorize the capacity_margin code some more to use it in both places in a consistent way ? This could be done in a separate patch, though. Thanks, Quentin