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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 12E74C2BA2B for ; Mon, 13 Apr 2020 20:33:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EBEBF20663 for ; Mon, 13 Apr 2020 20:33:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733290AbgDMUdF (ORCPT ); Mon, 13 Apr 2020 16:33:05 -0400 Received: from foss.arm.com ([217.140.110.172]:45986 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727877AbgDMUdD (ORCPT ); Mon, 13 Apr 2020 16:33:03 -0400 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 0C14930E; Mon, 13 Apr 2020 13:33:02 -0700 (PDT) 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 ADB4E3F6C4; Mon, 13 Apr 2020 13:33:00 -0700 (PDT) References: <245c792f0e580b3ca342ad61257f4c066ee0f84f.1586594833.git.rocking@linux.alibaba.com> <6f372bce-151e-79e1-2fda-d8b2bcf777d6@linux.alibaba.com> User-agent: mu4e 0.9.17; emacs 26.3 From: Valentin Schneider To: Peng Wang Cc: 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, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/fair: Simplify the code of should_we_balance() Message-ID: In-reply-to: <6f372bce-151e-79e1-2fda-d8b2bcf777d6@linux.alibaba.com> Date: Mon, 13 Apr 2020 21:32:37 +0100 MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/20 09:42, Peng Wang wrote: > 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. >> It's not really changing much, but if it helps making it a bit more readable, why not. Small nit below. Reviewed-by: Valentin Schneider >> 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? */ Nit: That should be either "the balance CPU" or "the first CPU in the group balance mask" >> + return group_balance_cpu(sg) == env->dst_cpu; >> } >> >> /* >> > > +juri.lelli@redhat.com