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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 03371C34026 for ; Tue, 18 Feb 2020 16:47:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D74D024649 for ; Tue, 18 Feb 2020 16:47:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726725AbgBRQrB (ORCPT ); Tue, 18 Feb 2020 11:47:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:32838 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726399AbgBRQrB (ORCPT ); Tue, 18 Feb 2020 11:47:01 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E8E15208C4; Tue, 18 Feb 2020 16:46:59 +0000 (UTC) Date: Tue, 18 Feb 2020 11:46:58 -0500 From: Steven Rostedt To: Qais Yousef Cc: Dietmar Eggemann , Ingo Molnar , Peter Zijlstra , Pavan Kondeti , Juri Lelli , Vincent Guittot , Ben Segall , Mel Gorman , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] sched/rt: cpupri_find: implement fallback mechanism for !fit case Message-ID: <20200218114658.74236b3c@gandalf.local.home> In-Reply-To: <20200217234549.rpv3ns7bd7l6twqu@e107158-lin> References: <20200214163949.27850-1-qais.yousef@arm.com> <20200214163949.27850-2-qais.yousef@arm.com> <20200217234549.rpv3ns7bd7l6twqu@e107158-lin> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 17 Feb 2020 23:45:49 +0000 Qais Yousef wrote: > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -14,6 +14,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun); > > struct rt_bandwidth def_rt_bandwidth; > > +typedef bool (*fitness_fn_t)(struct task_struct *p, int cpu); > + > static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer) > { > struct rt_bandwidth *rt_b = > @@ -1708,6 +1710,7 @@ static int find_lowest_rq(struct task_struct *task) > struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask); > int this_cpu = smp_processor_id(); > int cpu = task_cpu(task); > + fitness_fn_t fitness_fn; > > /* Make sure the mask is initialized first */ > if (unlikely(!lowest_mask)) > @@ -1716,8 +1719,17 @@ static int find_lowest_rq(struct task_struct *task) > if (task->nr_cpus_allowed == 1) > return -1; /* No other targets possible */ > > + /* > + * Help cpupri_find avoid the cost of looking for a fitting CPU when > + * not really needed. > + */ > + if (static_branch_unlikely(&sched_asym_cpucapacity)) > + fitness_fn = rt_task_fits_capacity; > + else > + fitness_fn = NULL; > + > if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask, > - rt_task_fits_capacity)) > + fitness_fn)) > return -1; /* No targets found */ > > /* If we are going to use static branches, then lets just remove the parameter totally. That is, make two functions (with helpers), where one needs this fitness function the other does not. if (static_branch_unlikely(&sched_asym_cpu_capacity)) ret = cpupri_find_fitness(...); else ret = cpupri_find(...); if (!ret) return -1; Something like that? -- Steve