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 5324FC433F5 for ; Thu, 14 Apr 2022 09:04:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240040AbiDNJGX (ORCPT ); Thu, 14 Apr 2022 05:06:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241588AbiDNJGF (ORCPT ); Thu, 14 Apr 2022 05:06:05 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id BBC3C6C1C8 for ; Thu, 14 Apr 2022 02:02:58 -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 68D0E139F; Thu, 14 Apr 2022 02:02:58 -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 953713F5A1; Thu, 14 Apr 2022 02:02:55 -0700 (PDT) Message-ID: Date: Thu, 14 Apr 2022 11:02:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH 1/1] [PATCH v2]sched/pelt: Refine the enqueue_load_avg calculate method Content-Language: en-US To: Kuyo Chang , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Matthias Brugger Cc: wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org References: <20220414015940.9537-1-kuyo.chang@mediatek.com> From: Dietmar Eggemann In-Reply-To: <20220414015940.9537-1-kuyo.chang@mediatek.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 14/04/2022 03:59, Kuyo Chang wrote: > From: kuyo chang [...] > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index d4bd299d67ab..159274482c4e 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -3829,10 +3829,12 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s > > se->avg.runnable_sum = se->avg.runnable_avg * divider; > > - se->avg.load_sum = divider; > - if (se_weight(se)) { > + se->avg.load_sum = se->avg.load_avg * divider; > + if (se_weight(se) < se->avg.load_sum) { > se->avg.load_sum = > - div_u64(se->avg.load_avg * se->avg.load_sum, se_weight(se)); > + div_u64(se->avg.load_sum, se_weight(se)); Seems that this will fit on one line now. No braces needed then. > + } else { > + se->avg.load_sum = 1; > } > > enqueue_load_avg(cfs_rq, se); Looks like taskgroups are not affected since they get always online with cpu.shares/weight = 1024 (cgroup v1): cpu_cgroup_css_online() -> online_fair_sched_group() -> attach_entity_cfs_rq() -> attach_entity_load_avg() And reweight_entity() does not have this issue. Tested with `qemu-system-x86_64 ... cores=64 ... -enable-kvm` and weight=88761 for nice=0 tasks plus forcing se->avg.load_avg = 1 before the div_u64() in attach_entity_load_avg(). Tested-by: Dietmar Eggemann