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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 A89F8C3F2D8 for ; Fri, 6 Mar 2020 04:24:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 82C53208C3 for ; Fri, 6 Mar 2020 04:24:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726905AbgCFEX1 (ORCPT ); Thu, 5 Mar 2020 23:23:27 -0500 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:54612 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726251AbgCFEX1 (ORCPT ); Thu, 5 Mar 2020 23:23:27 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R911e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01f04391;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0Trni2vY_1583468602; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0Trni2vY_1583468602) by smtp.aliyun-inc.com(127.0.0.1); Fri, 06 Mar 2020 12:23:22 +0800 Subject: Re: [RFC PATCH] sched: fix the nonsense shares when load of cfs_rq is too, small To: Vincent Guittot Cc: Ben Segall , Peter Zijlstra , Ingo Molnar , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Mel Gorman , "open list:SCHEDULER" References: <44fa1cee-08db-e4ab-e5ab-08d6fbd421d7@linux.alibaba.com> <20200303195245.GF2596@hirez.programming.kicks-ass.net> <1180c6cd-ff61-2c9f-d689-ffe58f8c5a68@linux.alibaba.com> From: =?UTF-8?B?546L6LSH?= Message-ID: <12f79b83-491c-4b4b-0581-d23bdcec7c0c@linux.alibaba.com> Date: Fri, 6 Mar 2020 12:23:22 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/3/5 δΈ‹εˆ3:53, Vincent Guittot wrote: > On Thu, 5 Mar 2020 at 02:14, ηŽ‹θ΄‡ wrote: [snip] >>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c >>> index fcc968669aea..6d7a9d72d742 100644 >>> --- a/kernel/sched/fair.c >>> +++ b/kernel/sched/fair.c >>> @@ -3179,9 +3179,9 @@ static long calc_group_shares(struct cfs_rq *cfs_rq) >>> long tg_weight, tg_shares, load, shares; >>> struct task_group *tg = cfs_rq->tg; >>> >>> - tg_shares = READ_ONCE(tg->shares); >>> + tg_shares = scale_load_down(READ_ONCE(tg->shares)); >>> >>> - load = max(scale_load_down(cfs_rq->load.weight), cfs_rq->avg.load_avg); >>> + load = max(cfs_rq->load.weight, scale_load(cfs_rq->avg.load_avg)); >>> >>> tg_weight = atomic_long_read(&tg->load_avg); >> >> Get the point, but IMHO fix scale_load_down() sounds better, to >> cover all the similar cases, let's first try that way see if it's >> working :-) > > The problem with this solution is that the avg.load_avg of gse or > cfs_rq might stay to 0 because it uses > scale_load_down(se/cfs_rq->load.weight) Will cfs_rq->load.weight be zero too without scale down? If cfs_rq->load.weight got at least something, the load will not be zero after pick the max, correct? Regards, Michael Wang > >> >> Regards, >> Michael Wang >> >>> >>> >>>