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=-9.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 AE0A4C433DF for ; Thu, 20 Aug 2020 14:19:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7DEEA20674 for ; Thu, 20 Aug 2020 14:19:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Phws8BHU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727895AbgHTOTv (ORCPT ); Thu, 20 Aug 2020 10:19:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45414 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726947AbgHTOTo (ORCPT ); Thu, 20 Aug 2020 10:19:44 -0400 Received: from mail-oo1-xc41.google.com (mail-oo1-xc41.google.com [IPv6:2607:f8b0:4864:20::c41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90548C061385 for ; Thu, 20 Aug 2020 07:19:44 -0700 (PDT) Received: by mail-oo1-xc41.google.com with SMTP id r6so438214oon.13 for ; Thu, 20 Aug 2020 07:19:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LQb9WVGZOx9n9j1FigmsnSqdEAP41Eibw43enyJulIg=; b=Phws8BHUL0rUuOaS64E2fTWRZt9Xw776XjmJ2R1c/Hs4o7LUXA/dRJkOBCvjOR38Qm k1/SI/7I9n+X2CSLxuurpdv3E+7JZ8jK7n7+cQ/BPmCzXBdTaQWkfR9GN2cUgVn5lGLa G/fWMnjIvdIaYf2gOXJ83vUsrFRSkG0J60nkpCxtBv01hK9A/oIdsBnDEUvSZu39MHXp T/YsqM4ksVBjDaKSYM2ZYiIyTkIF/ZY+u9QotE0y9ifo8nK4tr7n6gmGV6dbBslWSc/d J/Nim7X6TUEoCYaZDnbBpBifL53hflbz05yy3N8Up7dTK0Ub0xP0e3snxl274kmA6xde KZFQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LQb9WVGZOx9n9j1FigmsnSqdEAP41Eibw43enyJulIg=; b=Z3PtYeLPAF63scigEg6eZhyUHu5GngGwiZfHYXsLp1R6hUP0Z9wI+zVbPPs2i/0/Hh +yCPx/bZCpjUKSv+hi9dibNHFA99h+Sni4IcKhpipa/flHKvG4iJcaX+KjfU8mVKa2oH AWpuly+v9dgXTkUZ+cftSwWBiTzZFJvR9nc+4Q+uK4CqUR11+lZMYu3NevXPfpDSWy+p Ft4Hsw9Z52HG0j+l1p9Pw6p7f/d3q7NSaKUGpreSqMB0eLw/zt5X37X/bfAEBU+duqVw CU38eE8OK7LsOyMJRnEbSxXda9jj6awIlEWhe3LRj5SqdepTmp1jScF/lEN4+2FjH0dl e5HQ== X-Gm-Message-State: AOAM530ObzwoRmaMs6WB2xlWPNcmiTECUtLYSyGJy0l4u/naYIjPTa65 Mv5uPYWrq3v3rc9SXil3J8nzqIvZ+ayfirOyB53AeEHaVPvPEQ== X-Google-Smtp-Source: ABdhPJyhjS63/b7WDVE9wM6oUnylRf6OwbI259OrGMTGANyQn2bOCLku2JrRZ5P9CrNozQGO1Sgqpy0LvqHAo91+ycY= X-Received: by 2002:a4a:d2d8:: with SMTP id j24mr2588594oos.82.1597933182847; Thu, 20 Aug 2020 07:19:42 -0700 (PDT) MIME-Version: 1.0 References: <20200820120025.74460-1-benbjiang@tencent.com> <20200820125829.GT2674@hirez.programming.kicks-ass.net> In-Reply-To: <20200820125829.GT2674@hirez.programming.kicks-ass.net> From: Jiang Biao Date: Thu, 20 Aug 2020 22:19:32 +0800 Message-ID: Subject: Re: [PATCH] sched/fair: avoid vruntime compensation for SCHED_IDLE task To: Peter Zijlstra Cc: Vincent Guittot , Ingo Molnar , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , linux-kernel , Jiang Biao Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 20 Aug 2020 at 20:58, wrote: > > On Thu, Aug 20, 2020 at 02:51:06PM +0200, Vincent Guittot wrote: > > On Thu, 20 Aug 2020 at 14:00, Jiang Biao wrote: > > > > > > From: Jiang Biao > > > > > > Vruntime compensation has been down in place_entity() to > > > boot the waking procedure for fair tasks. There is no need to > > > > s/boot/boost/ ? > > > > > do that for SCHED_IDLE task actually. > > > > > > Not compensating vruntime for SCHED_IDLE task could make > > > SCHED_IDLE task more harmless for normal tasks. > > This is rather week. It would be much better if there's some actual data > to support this claim. I'll try to have a test and get some data. :) > > > > Signed-off-by: Jiang Biao > > > --- > > > 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 1a68a0536add..adff77676a0a 100644 > > > --- a/kernel/sched/fair.c > > > +++ b/kernel/sched/fair.c > > > @@ -4115,7 +4115,7 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) > > > vruntime += sched_vslice(cfs_rq, se); > > > > > > /* sleeps up to a single latency don't count. */ > > > - if (!initial) { > > > + if (!initial && likely(!task_has_idle_policy(task_of(se)))) { > > > > What if se is not a task ? > > Then we very much need it, because it might have fair tasks inside. I > suppose you could do something complicated with idle_h_nr_running, but > is all that really worth the effort? Would it be better to limit to task se case? like + if (!initial && likely(!entity_is_task(se) || !task_has_idle_policy(task_of(se)))) { > > > > unsigned long thresh = sysctl_sched_latency; > > > > > > /* > > > -- > > > 2.21.0 > > >