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 6A4E6C433EF for ; Wed, 20 Jul 2022 13:48:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240212AbiGTNse (ORCPT ); Wed, 20 Jul 2022 09:48:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229704AbiGTNs2 (ORCPT ); Wed, 20 Jul 2022 09:48:28 -0400 Received: from mail-pj1-x1029.google.com (mail-pj1-x1029.google.com [IPv6:2607:f8b0:4864:20::1029]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46F6B5F116 for ; Wed, 20 Jul 2022 06:48:27 -0700 (PDT) Received: by mail-pj1-x1029.google.com with SMTP id o5-20020a17090a3d4500b001ef76490983so2242178pjf.2 for ; Wed, 20 Jul 2022 06:48:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=18rSbs7d/JpSNyiTxLgkJ7GYY5R87zF+IcF/GENE0J4=; b=67O1Fi8UrJgV3Nq/UWYzs2JKLXRcqaq4CPG1/gwUHOcQo7tklMr5cbEbFyy2MP7T0P Ue2wdG5Ln6afJpt5avWJli8H6wpJyoJpgtiM1ZTIlf8dWqjJ+PP7XDON19RRT7pp+4Zu XpSRMEz2mrmwNGBmK1WdZELOsRl0Y5ettt/4BhGy93D/3TMRjfJCcJLkTd/COwu0HsuJ N54t/ICmxVqmfxgP7R8U6ZwmLQJNV0opf227SYyCfLg4m6Mh23jljiyMRKk4hq9pXmKC wA+9+aAXK3hIVKQzMCqA61mz5LtNu5E8Dh2XIJfCh2HHjIzVFJGriF3Fosr1dSMTQT/e PzFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=18rSbs7d/JpSNyiTxLgkJ7GYY5R87zF+IcF/GENE0J4=; b=IkcPi0i396cOxy82e973NqFscdaMwkUdZ7aoVaQLnaPmcxam+S6Mvl0X86f0TJM/OD VFsUpKAJ6OFz0TZ09MGiFvrZiyr72dn/VtpxtZ4ZjrHtT56iqnT1iE3OJt/a4a11/IvC NNshz1A31uuDXIsAd6uomT7F+xkuQnfWK2Rctjd/EsqcdZidqi1w4PQ1qSK9nH0rnXJL SQEpnQV/gYE4Pfj+jGyDyDKt0RW6NdIQD+IQjosvCSWLX68hANTq/vNHHPijuiAmvAJz 9dc6jQT0HUvn02Ra/fBN0EJN2zAWBJx7WtXapcKbJma28q7XSjCndsuqGGtCK3PhOo2Q vuXA== X-Gm-Message-State: AJIora/DLpKB9i1ymsv68HQAsMDsfywK0QRAEiQIyKZ8hZdrDJOzejQj 5OPogeDutkh/0nenpESbWqaXJA== X-Google-Smtp-Source: AGRyM1udeA1DCGlNyKn43n1gVBBDhLdKURr17x3EKB4UBSjxIi/rXs8pVZy0vqW9CafAzyk4oF91FQ== X-Received: by 2002:a17:902:ef48:b0:16a:1d4b:22ca with SMTP id e8-20020a170902ef4800b0016a1d4b22camr38566565plx.6.1658324906639; Wed, 20 Jul 2022 06:48:26 -0700 (PDT) Received: from [10.4.100.137] ([139.177.225.240]) by smtp.gmail.com with ESMTPSA id t68-20020a625f47000000b0052aaf7fdf2esm13518406pfb.137.2022.07.20.06.48.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Jul 2022 06:48:26 -0700 (PDT) Message-ID: Date: Wed, 20 Jul 2022 21:48:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.0.1 Subject: Re: [External] Re: [PATCH v2 08/10] sched/fair: fix load tracking for new forked !fair task Content-Language: en-US To: Vincent Guittot Cc: mingo@redhat.com, peterz@infradead.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, vschneid@redhat.com, linux-kernel@vger.kernel.org References: <20220713040430.25778-1-zhouchengming@bytedance.com> <20220713040430.25778-9-zhouchengming@bytedance.com> From: Chengming Zhou In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/7/19 20:35, Vincent Guittot wrote: > On Wed, 13 Jul 2022 at 06:05, Chengming Zhou > wrote: >> >> New forked !fair task will set its sched_avg last_update_time to >> the pelt_clock of cfs_rq, after a while in switched_to_fair(): >> >> switched_to_fair >> attach_task_cfs_rq >> attach_entity_cfs_rq >> update_load_avg >> __update_load_avg_se(now, cfs_rq, se) >> >> the delta (now - sa->last_update_time) will contribute/decay sched_avg >> depends on the task running/runnable status at that time. >> >> This patch don't set sched_avg last_update_time of new forked !fair >> task, leave it to 0. So later in update_load_avg(), we don't need to >> contribute/decay the wrong delta (now - sa->last_update_time). > > As mentioned in patch 7, I think it's wrong to not decay the init > value of !fair task because they become obsolete if not used quickly > (so we are decaying them) > > It would be better to not set them at all in the case of !fair task So just leave !fair task sched_avg to 0 and last_update_time == 0, right? Thanks. > >> >> Signed-off-by: Chengming Zhou >> --- >> kernel/sched/fair.c | 18 ++---------------- >> 1 file changed, 2 insertions(+), 16 deletions(-) >> >> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >> index 51fc20c161a3..50f65a2ede32 100644 >> --- a/kernel/sched/fair.c >> +++ b/kernel/sched/fair.c >> @@ -849,22 +849,8 @@ void post_init_entity_util_avg(struct task_struct *p) >> >> sa->runnable_avg = sa->util_avg; >> >> - if (p->sched_class != &fair_sched_class) { >> - /* >> - * For !fair tasks do: >> - * >> - update_cfs_rq_load_avg(now, cfs_rq); >> - attach_entity_load_avg(cfs_rq, se); >> - switched_from_fair(rq, p); >> - * >> - * such that the next switched_to_fair() has the >> - * expected state. >> - */ >> - se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq); >> - return; >> - } >> - >> - attach_entity_cfs_rq(se); >> + if (p->sched_class == &fair_sched_class) >> + attach_entity_cfs_rq(se); >> } >> >> #else /* !CONFIG_SMP */ >> -- >> 2.36.1 >>