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=-15.9 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 787D1C47096 for ; Thu, 3 Jun 2021 10:42:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 62AD9613B8 for ; Thu, 3 Jun 2021 10:42:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230056AbhFCKoZ (ORCPT ); Thu, 3 Jun 2021 06:44:25 -0400 Received: from foss.arm.com ([217.140.110.172]:37850 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229758AbhFCKoY (ORCPT ); Thu, 3 Jun 2021 06:44:24 -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 1C5001063; Thu, 3 Jun 2021 03:42:40 -0700 (PDT) Received: from [192.168.178.6] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5EEAB3F774; Thu, 3 Jun 2021 03:42:38 -0700 (PDT) Subject: Re: [PATCH] sched/pelt: check that *_avg are null when *_sum are To: Vincent Guittot , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, linux-kernel@vger.kernel.org Cc: odin@uged.al References: <20210601155328.19487-1-vincent.guittot@linaro.org> From: Dietmar Eggemann Message-ID: <438d95b4-330b-8a4b-a800-bab15db4f170@arm.com> Date: Thu, 3 Jun 2021 12:42:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <20210601155328.19487-1-vincent.guittot@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/06/2021 17:53, Vincent Guittot wrote: > Check that we never break the rule that pelt's avg values are null if > pelt's sum are. > > Signed-off-by: Vincent Guittot > --- > > This is what I used for patch 20210601085832.12626-1-vincent.guittot@linaro.org > > kernel/sched/fair.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index a2c30e52de76..c17feadeafcc 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -8021,6 +8021,15 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq) > if (cfs_rq->avg.runnable_sum) > return false; > > + /* > + * _avg must be null when _sum are null because _avg = _sum / divider > + * Make sure that rounding and/or propagation of PELT values never > + * break this. > + */ > + SCHED_WARN_ON(cfs_rq->avg.load_avg || > + cfs_rq->avg.util_avg || > + cfs_rq->avg.runnable_avg); > + > return true; > } Reviewed-by: Dietmar Eggemann