From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752909AbcHONj5 (ORCPT ); Mon, 15 Aug 2016 09:39:57 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:53952 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752428AbcHONj4 (ORCPT ); Mon, 15 Aug 2016 09:39:56 -0400 Date: Mon, 15 Aug 2016 15:39:49 +0200 From: Peter Zijlstra To: Morten Rasmussen Cc: mingo@redhat.com, dietmar.eggemann@arm.com, yuyang.du@intel.com, vincent.guittot@linaro.org, mgalbraith@suse.de, sgurrappadi@nvidia.com, freedom.tan@mediatek.com, keita.kobayashi.ym@renesas.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 09/13] sched/fair: Let asymmetric cpu configurations balance at wake-up Message-ID: <20160815133949.GT6879@twins.programming.kicks-ass.net> References: <1469453670-2660-1-git-send-email-morten.rasmussen@arm.com> <1469453670-2660-10-git-send-email-morten.rasmussen@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1469453670-2660-10-git-send-email-morten.rasmussen@arm.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 25, 2016 at 02:34:26PM +0100, Morten Rasmussen wrote: Because I forgot _again_, I added: /* * Disable WAKE_AFFINE in the case where task @p doesn't fit in the * capacity of either the waking CPU @cpu or the previous CPU @prev_cpu. * * In that case WAKE_AFFINE doesn't make sense and we'll let * BALANCE_WAKE sort things out. */ > +static int wake_cap(struct task_struct *p, int cpu, int prev_cpu) > +{ > + long min_cap, max_cap; > + > + min_cap = min(capacity_orig_of(prev_cpu), capacity_orig_of(cpu)); > + max_cap = cpu_rq(cpu)->rd->max_cpu_capacity; There's a tiny hole here, which I'm fairly sure we don't care about. If @p last ran on @prev_cpu before @prev_cpu was split from @rd this doesn't 'work' right. > + /* Minimum capacity is close to max, no need to abort wake_affine */ > + if (max_cap - min_cap < max_cap >> 3) > + return 0; > + > + return min_cap * 1024 < task_util(p) * capacity_margin; > +} > + > /* > * select_task_rq_fair: Select target runqueue for the waking task in domains > * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, > @@ -5389,7 +5414,8 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f > > if (sd_flag & SD_BALANCE_WAKE) { > record_wakee(p); > - want_affine = !wake_wide(p) && cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); > + want_affine = !wake_wide(p) && !wake_cap(p, cpu, prev_cpu) > + && cpumask_test_cpu(cpu, tsk_cpus_allowed(p)); > } > > rcu_read_lock(); > -- > 1.9.1 >