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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DC179C43334 for ; Thu, 14 Jul 2022 12:32:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237950AbiGNMcV (ORCPT ); Thu, 14 Jul 2022 08:32:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239014AbiGNMcL (ORCPT ); Thu, 14 Jul 2022 08:32:11 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AE7BF3CBD2 for ; Thu, 14 Jul 2022 05:32:10 -0700 (PDT) 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 DA45315A1; Thu, 14 Jul 2022 05:32:10 -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 2B9213F792; Thu, 14 Jul 2022 05:32:09 -0700 (PDT) Message-ID: Date: Thu, 14 Jul 2022 14:31:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v2 05/10] sched/fair: reset sched_avg last_update_time before set_task_rq() Content-Language: en-US To: Chengming Zhou , mingo@redhat.com, peterz@infradead.org, vincent.guittot@linaro.org, rostedt@goodmis.org, bsegall@google.com, vschneid@redhat.com Cc: linux-kernel@vger.kernel.org References: <20220713040430.25778-1-zhouchengming@bytedance.com> <20220713040430.25778-6-zhouchengming@bytedance.com> From: Dietmar Eggemann In-Reply-To: <20220713040430.25778-6-zhouchengming@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13/07/2022 06:04, Chengming Zhou wrote: > set_task_rq() -> set_task_rq_fair() will try to synchronize the blocked > task's sched_avg when migrate, which is not needed for already detached > task. > > task_change_group_fair() will detached the task sched_avg from prev cfs_rq > first, so reset sched_avg last_update_time before set_task_rq() to avoid that. > > Signed-off-by: Chengming Zhou Reviewed-by: Dietmar Eggemann > --- > kernel/sched/fair.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 8992ce5e73d2..171bc22bc142 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -11637,12 +11637,12 @@ void init_cfs_rq(struct cfs_rq *cfs_rq) > static void task_change_group_fair(struct task_struct *p) > { > detach_task_cfs_rq(p); > - set_task_rq(p, task_cpu(p)); > > #ifdef CONFIG_SMP > /* Tell se's cfs_rq has been changed -- migrated */ > p->se.avg.last_update_time = 0; > #endif > + set_task_rq(p, task_cpu(p)); > attach_task_cfs_rq(p); > } >