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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no 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 32421C3A59F for ; Mon, 26 Aug 2019 15:46:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0479120874 for ; Mon, 26 Aug 2019 15:46:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="kVhS7eBY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729987AbfHZPqI (ORCPT ); Mon, 26 Aug 2019 11:46:08 -0400 Received: from mail-lf1-f68.google.com ([209.85.167.68]:39423 "EHLO mail-lf1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727850AbfHZPqH (ORCPT ); Mon, 26 Aug 2019 11:46:07 -0400 Received: by mail-lf1-f68.google.com with SMTP id x3so12645633lfn.6 for ; Mon, 26 Aug 2019 08:46:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=aUtEkSG5kTsp7YmVa7FAJXb4NP4nolqiwqp/5TmmW1o=; b=kVhS7eBYbwJl2W+rs3K5lxwHETdSIbREf93+C7I/bFgaHC2ZAcLeenp8Hp/jgZ1XOE Li6yMP4VViQQj90iHFUBWNN5yIFr/GIvQy/sdzb9ZjESIeoWa9khQKepNPhSG+a/YJIU xyyyYFNj9pRJV0eMdfjZAgD5c+i45QQkJw0wRU7qE7uTaUH4Zp4coOM55Bmi8U5SBVj6 HpjYfpV0ubPA70psLYuGuPrzTL1WH0Sb+15IeQOiSM70JoHIAX7WH+N5GQwZxthhTlUt fXbUbJY+bOdTwNA40/706RfheGMTMmUUSX46up1T9HAR4soVa/MZmhhdEXaNvg7D8qsK Umdw== 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=aUtEkSG5kTsp7YmVa7FAJXb4NP4nolqiwqp/5TmmW1o=; b=IJ5296NgdTsdfgAwlwLHs4f4BH0RoyWJshBTsX0xo1DJ2F4IUlrB3tg1KK5wm1+97a kSpgRdz5IAIazJ6O+UXFVIEUiNjnUTnsjofu9YtmRx1cqQGv3fM/AFqgzvK2M4177VIp pkh9w4iIegpNPkMPacJJVR/BqK4OsvEJreoVHi/9cPk4AMz1SEGCGyCPnVFontk08xer xh6DbGOiXcjols69B8XjCQiDYJnCEGdbf2rZKU5vhDqwMFXqCdBeMtk4w9IIZIHtkyrF NuBUvt/c0e7+U+j93/TfG0SKNj0+H+uNLWCBKdo3wtWP+ni+N43AnWdGH1Hq1qhacTPd s3Qg== X-Gm-Message-State: APjAAAVDsiMJ0oNdw7Kn5uPa4/UwmOP/wpL5hHn2o/tgTmdlS8guAPcZ iWPq4NfeyjkVO00UR4oYZNeMTQ4iBoGPJGC7qYhp8g== X-Google-Smtp-Source: APXvYqyQWc/RQAKI+R+gDKTzw8gV75oM0Rebwd3aJSKMRhRtu5WiZJEN5VTPwqeFhnT94uCkFiLDJAhffWsxIa3lkN0= X-Received: by 2002:ac2:546c:: with SMTP id e12mr10986869lfn.133.1566834365030; Mon, 26 Aug 2019 08:46:05 -0700 (PDT) MIME-Version: 1.0 References: <1564670424-26023-1-git-send-email-vincent.guittot@linaro.org> <1564670424-26023-7-git-send-email-vincent.guittot@linaro.org> <20190806160743.GW2332@hirez.programming.kicks-ass.net> In-Reply-To: <20190806160743.GW2332@hirez.programming.kicks-ass.net> From: Vincent Guittot Date: Mon, 26 Aug 2019 17:45:53 +0200 Message-ID: Subject: Re: [PATCH v2 6/8] sched/fair: use load instead of runnable load To: Peter Zijlstra Cc: linux-kernel , Ingo Molnar , Phil Auld , Valentin Schneider , Srikar Dronamraju , Quentin Perret , Dietmar Eggemann , Morten Rasmussen 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 Tue, 6 Aug 2019 at 18:07, Peter Zijlstra wrote: > > On Thu, Aug 01, 2019 at 04:40:22PM +0200, Vincent Guittot wrote: > > runnable load has been introduced to take into account the case > > where blocked load biases the load balance decision which was selecting > > underutilized group with huge blocked load whereas other groups were > > overloaded. > > > > The load is now only used when groups are overloaded. In this case, > > it's worth being conservative and taking into account the sleeping > > tasks that might wakeup on the cpu. > > This one scares me a little. I have the feeling I'm missing/forgetting > something. > > Also; while the regular load-balance (find-busiest) stuff is now all > aware of idle, this change also impacts wake_affine and find_idlest, and > they've not changed. Yes. I thought about this a bit before applying this changes to all cpu_runnable_load. -For wake_affine, it starts by looking at an idle cpu with wake_affine_idle which is similar in some way to the new load balance approach even if it might need more changes to align more closely both paths. -For find_idlest, it looks at the group with most spare capacity in priority and fall back to load. That being said I have overlooked that both load and runnable load are already used and cpu.load is saved twice instead of one. I can't remember detailed results but this patch is responsible of part of perf improvements described in the cover letter Also, I haven't touch the numa stats which still use runnable_load. But this should be addressed too