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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 84CADC433E0 for ; Wed, 6 Jan 2021 15:14:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 48CAF2311B for ; Wed, 6 Jan 2021 15:14:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726600AbhAFPO0 (ORCPT ); Wed, 6 Jan 2021 10:14:26 -0500 Received: from foss.arm.com ([217.140.110.172]:42478 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726011AbhAFPOZ (ORCPT ); Wed, 6 Jan 2021 10:14:25 -0500 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 417F8D6E; Wed, 6 Jan 2021 07:13:40 -0800 (PST) Received: from e113632-lin (e113632-lin.cambridge.arm.com [10.1.194.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C80233F719; Wed, 6 Jan 2021 07:13:38 -0800 (PST) From: Valentin Schneider To: Vincent Guittot , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, linux-kernel@vger.kernel.org Cc: Vincent Guittot Subject: Re: [PATCH 1/3] sched/fair: skip idle cfs_rq In-Reply-To: <20210106133419.2971-2-vincent.guittot@linaro.org> References: <20210106133419.2971-1-vincent.guittot@linaro.org> <20210106133419.2971-2-vincent.guittot@linaro.org> User-Agent: Notmuch/0.21 (http://notmuchmail.org) Emacs/26.3 (x86_64-pc-linux-gnu) Date: Wed, 06 Jan 2021 15:13:31 +0000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/01/21 14:34, Vincent Guittot wrote: > Don't waste time checking whether an idle cfs_rq could be the busiest > queue. Furthermore, this can end up selecting a cfs_rq with a high load > but being idle in case of migrate_load. > > Signed-off-by: Vincent Guittot Makes sense to me. Reviewed-by: Valentin Schneider > --- > kernel/sched/fair.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 04a3ce20da67..5428b8723e61 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -9389,8 +9389,11 @@ static struct rq *find_busiest_queue(struct lb_env *env, > if (rt > env->fbq_type) > continue; > > - capacity = capacity_of(i); > nr_running = rq->cfs.h_nr_running; > + if (!nr_running) > + continue; > + > + capacity = capacity_of(i); > > /* > * For ASYM_CPUCAPACITY domains, don't pick a CPU that could > -- > 2.17.1