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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 C50F4C54FCB for ; Thu, 23 Apr 2020 14:30:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1C0F20728 for ; Thu, 23 Apr 2020 14:30:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728158AbgDWOaL (ORCPT ); Thu, 23 Apr 2020 10:30:11 -0400 Received: from foss.arm.com ([217.140.110.172]:41186 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726060AbgDWOaL (ORCPT ); Thu, 23 Apr 2020 10:30:11 -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 830B731B; Thu, 23 Apr 2020 07:30:10 -0700 (PDT) Received: from [192.168.0.7] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 153033F6CF; Thu, 23 Apr 2020 07:30:08 -0700 (PDT) Subject: Re: [PATCH] sched/pelt: sync util/runnable_sum with PELT window when propagating To: Vincent Guittot , mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, linux-kernel@vger.kernel.org References: <20200422151401.9147-1-vincent.guittot@linaro.org> From: Dietmar Eggemann Message-ID: <23c1cbb8-7335-80ca-cf40-8abc5c1463f4@arm.com> Date: Thu, 23 Apr 2020 16:30:02 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200422151401.9147-1-vincent.guittot@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/04/2020 17:14, Vincent Guittot wrote: > update_tg_cfs_util/runnable() propagate the impact of the attach/detach of > an entity down into the cfs_rq hierarchy which must keep the sync with > the current pelt window. > > Even if we can't sync child rq and its group se, we can sync the group se So we have gcfs --> tg --> gse ________________| | V cfs ---> tg (root) | V rq here. What is 'child rq' for 'group se' here? I guess 'parent cfs_rq' is cfs_rq. > and parent cfs_rq with current PELT window. In fact, we must keep them sync > in order to stay also synced with others se and group se that are already > attached to the cfs_rq. > > Signed-off-by: Vincent Guittot > --- > kernel/sched/fair.c | 26 ++++++-------------------- > 1 file changed, 6 insertions(+), 20 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 02f323b85b6d..ca6aa89c88f2 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -3441,52 +3441,38 @@ static inline void > update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq) > { > long delta = gcfs_rq->avg.util_avg - se->avg.util_avg; > + u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib; > > /* Nothing to update */ > if (!delta) > return; > > - /* > - * The relation between sum and avg is: > - * > - * LOAD_AVG_MAX - 1024 + sa->period_contrib > - * > - * however, the PELT windows are not aligned between grq and gse. > - */ > - > /* Set new sched_entity's utilization */ > se->avg.util_avg = gcfs_rq->avg.util_avg; > - se->avg.util_sum = se->avg.util_avg * LOAD_AVG_MAX; > + se->avg.util_sum = se->avg.util_avg * divider; divider uses cfs_rq but we sync se->avg.util_avg with gcfs_rq here. But since avg.period_contrib of cfs_rq and gcfs_rq are the same this should work. > /* Update parent cfs_rq utilization */ > add_positive(&cfs_rq->avg.util_avg, delta); > - cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * LOAD_AVG_MAX; > + cfs_rq->avg.util_sum = cfs_rq->avg.util_avg * divider; Looks like that avg.last_update_time of se (group entity), it's gcfs_rq and cfs_rq is always the same in update_tg_cfs_[util\|runnable]. So that means the PELT windows are aligned for cfs_rqs and group se's? And if we want to enforce this for cfs_rq and task, we have sync_entity_load_avg(). [...]