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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 20252C2BA2B for ; Sun, 12 Apr 2020 08:42:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC4B7206DA for ; Sun, 12 Apr 2020 08:42:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726837AbgDLIm0 (ORCPT ); Sun, 12 Apr 2020 04:42:26 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:57124 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725903AbgDLImZ (ORCPT ); Sun, 12 Apr 2020 04:42:25 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R311e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04407;MF=rocking@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0TvGWLBf_1586680942; Received: from 30.25.201.141(mailfrom:rocking@linux.alibaba.com fp:SMTPD_---0TvGWLBf_1586680942) by smtp.aliyun-inc.com(127.0.0.1); Sun, 12 Apr 2020 16:42:22 +0800 From: Peng Wang Subject: Re: [PATCH] sched/fair: Simplify the code of should_we_balance() To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de Cc: linux-kernel@vger.kernel.org References: <245c792f0e580b3ca342ad61257f4c066ee0f84f.1586594833.git.rocking@linux.alibaba.com> Message-ID: <6f372bce-151e-79e1-2fda-d8b2bcf777d6@linux.alibaba.com> Date: Sun, 12 Apr 2020 16:42:21 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <245c792f0e580b3ca342ad61257f4c066ee0f84f.1586594833.git.rocking@linux.alibaba.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/11/20 5:20 PM, Peng Wang wrote: > We only consider group_balance_cpu() after there is no idle > cpu. So, just do comparison before return at these two cases. > > Signed-off-by: Peng Wang > --- > kernel/sched/fair.c | 16 +++++----------- > 1 file changed, 5 insertions(+), 11 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 1ea3ddd..81b2c647 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -9413,7 +9413,7 @@ static int active_load_balance_cpu_stop(void *data); > static int should_we_balance(struct lb_env *env) > { > struct sched_group *sg = env->sd->groups; > - int cpu, balance_cpu = -1; > + int cpu; > > /* > * Ensure the balancing environment is consistent; can happen > @@ -9434,18 +9434,12 @@ static int should_we_balance(struct lb_env *env) > if (!idle_cpu(cpu)) > continue; > > - balance_cpu = cpu; > - break; > + /* Are we the first idle CPU? */ > + return cpu == env->dst_cpu; > } > > - if (balance_cpu == -1) > - balance_cpu = group_balance_cpu(sg); > - > - /* > - * First idle CPU or the first CPU(busiest) in this sched group > - * is eligible for doing load balancing at this and above domains. > - */ > - return balance_cpu == env->dst_cpu; > + /* Are we the first balance CPU of this group? */ > + return group_balance_cpu(sg) == env->dst_cpu; > } > > /* > +juri.lelli@redhat.com