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=-3.8 required=3.0 tests=BAYES_00,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 92869C2D0A3 for ; Fri, 6 Nov 2020 16:07:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30B6722202 for ; Fri, 6 Nov 2020 16:07:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="LBWs1kSg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726791AbgKFQHP (ORCPT ); Fri, 6 Nov 2020 11:07:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59116 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725868AbgKFQHO (ORCPT ); Fri, 6 Nov 2020 11:07:14 -0500 Received: from mail-lf1-x143.google.com (mail-lf1-x143.google.com [IPv6:2a00:1450:4864:20::143]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E29BC0613CF for ; Fri, 6 Nov 2020 08:07:13 -0800 (PST) Received: by mail-lf1-x143.google.com with SMTP id u18so2637984lfd.9 for ; Fri, 06 Nov 2020 08:07:13 -0800 (PST) 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=gcmj1ukv7K42dhp/oVEaqtNUwjrAJVWvGdsiH5MZxzQ=; b=LBWs1kSgkTH7BzcDw1dW36l1s5vt8FR4tN72pUg8QJKbCkDNA/U/+7ZCyc6yUecXBf 24eRuxkMu/ESPXvkbHhh73LJ+nswsF1YZDm9I42OVx/c9lq/PDjftC8Dp7PrQzKzx9j0 c3D+g2oXC6bARlObQTKDAOXSkDbTD1Kbf8Y0xQ+R8slXE3q9EZis9XOp/uwk6yPq9s1f DMsD7YKWG3WXGVRH3RhO9gSSS0FhghdPOpUqCtLbZeDgben+Kh2RY1BPm0DeaMiBfy+P HL/gyLx3NVDrG9vWMp3J475mfzXK0dFZnspoHcKL8PGAix3gFYivbujsoxkFuTAHveTc aslA== 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=gcmj1ukv7K42dhp/oVEaqtNUwjrAJVWvGdsiH5MZxzQ=; b=EBoBTjEgJ5tUGZTfuaHKNHWqjf6Ox/YZZlqKYCvSsI/P4Ur8P6cLHAFJthoGBpB+X9 gpIfq4igViu22dYGLmFpBzjaU+rTcnW5mWwWWLVGI6mfwoEH1ejuCLQz1FfDf4LAXyNJ pUV48jBXTFKr7zfVQzTxDL70qaCImSGDpd7NZRmo2hb6y/9ywFkhGAnu5/JHtO+Wtgwk 4JyNUwxn70CMNBqDlETRlZ3dkAVXNK98zPPMLSej5jBW6mfse/Q/v0KVE7nBB9KZNd2C ZCOYsOdAMjWoxnTrUyujj86E5TJ2dOvJQQwMNVmdIlU+IVeIxQq/Go2GK1OAZTJvbPsL DDiQ== X-Gm-Message-State: AOAM530nw5tNeqoz4VCcXDBuDTmyxGAxa+hGEE6aT5Zzb/rt61q5bec0 unZTEixXK+sU6MFga9HLqhGvf7WZeAV/BhbnZKmtSA== X-Google-Smtp-Source: ABdhPJzPV+96s9Sgi3pkLF1/g9jUHJXBhTnJjRhYfsaPk2Dy6Z08ahROTttBY3Mr+FzWzNh89Q3mVzYYm4XkGJ9Xd6E= X-Received: by 2002:ac2:5f4b:: with SMTP id 11mr1086333lfz.385.1604678831402; Fri, 06 Nov 2020 08:07:11 -0800 (PST) MIME-Version: 1.0 References: <20200714125941.4174-1-peter.puhov@linaro.org> <20201102105043.GB3371@techsingularity.net> <20201102144418.GB154641@lorien.usersys.redhat.com> <20201104094205.GI3306@suse.de> <20201106120303.GE3371@techsingularity.net> <20201106160010.GF3371@techsingularity.net> In-Reply-To: <20201106160010.GF3371@techsingularity.net> From: Vincent Guittot Date: Fri, 6 Nov 2020 17:06:59 +0100 Message-ID: Subject: Re: [PATCH v1] sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal To: Mel Gorman Cc: Phil Auld , Peter Puhov , linux-kernel , Robert Foley , Ingo Molnar , Peter Zijlstra , Juri Lelli , Dietmar Eggemann , Steven Rostedt , Ben Segall , Jirka Hladky Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 6 Nov 2020 at 17:00, Mel Gorman wrote: > > On Fri, Nov 06, 2020 at 02:33:56PM +0100, Vincent Guittot wrote: > > On Fri, 6 Nov 2020 at 13:03, Mel Gorman wrote: > > > > > > On Wed, Nov 04, 2020 at 09:42:05AM +0000, Mel Gorman wrote: > > > > While it's possible that some other factor masked the impact of the patch, > > > > the fact it's neutral for two workloads in 5.10-rc2 is suspicious as it > > > > indicates that if the patch was implemented against 5.10-rc2, it would > > > > likely not have been merged. I've queued the tests on the remaining > > > > machines to see if something more conclusive falls out. > > > > > > > > > > It's not as conclusive as I would like. fork_test generally benefits > > > across the board but I do not put much weight in that. > > > > > > Otherwise, it's workload and machine-specific. > > > > > > schbench: (wakeup latency sensitive), all machines benefitted from the > > > revert at the low utilisation except one 2-socket haswell machine > > > which showed higher variability when the machine was fully > > > utilised. > > > > There is a pending patch to should improve this bench: > > https://lore.kernel.org/patchwork/patch/1330614/ > > > > Ok, I've slotted this one in with a bunch of other stuff I wanted to run > over the weekend. That particular patch was on my radar anyway. It just > got bumped up the schedule a little bit. > > > > hackbench: Neutral except for the same 2-socket Haswell machine which > > > took an 8% performance penalty of 8% for smaller number of groups > > > and 4% for higher number of groups. > > > > > > pipetest: Mostly neutral except for the *same* machine showing an 18% > > > performance gain by reverting. > > > > > > kernbench: Shows small gains at low job counts across the board -- 0.84% > > > lowest gain up to 5.93% depending on the machine > > > > > > gitsource: low utilisation execution of the git test suite. This was > > > mostly a win for the revert. For the list of machines tested it was > > > > > > 14.48% gain (2 socket but SNC enabled to 4 NUMA nodes) > > > neutral (2 socket broadwell) > > > 36.37% gain (1 socket skylake machine) > > > 3.18% gain (2 socket broadwell) > > > 4.4% (2 socket EPYC 2) > > > 1.85% gain (2 socket EPYC 1) > > > > > > While it was clear-cut for 5.9, it's less clear-cut for 5.10-rc2 although > > > the gitsource shows some severe differences depending on the machine that > > > is worth being extremely cautious about. I would still prefer a revert > > > but I'm also extremely biased and I know there are other patches in the > > > > This one from Julia can also impact > > > > Which one? I'm guessing "[PATCH v2] sched/fair: check for idle core" Yes, Sorry I sent my answer before adding the link > > -- > Mel Gorman > SUSE Labs