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=-10.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,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 0C841C49EA6 for ; Thu, 24 Jun 2021 12:31:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EDB046054E for ; Thu, 24 Jun 2021 12:31:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231630AbhFXMeB (ORCPT ); Thu, 24 Jun 2021 08:34:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45508 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231682AbhFXMdr (ORCPT ); Thu, 24 Jun 2021 08:33:47 -0400 Received: from mail-lj1-x22c.google.com (mail-lj1-x22c.google.com [IPv6:2a00:1450:4864:20::22c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0C16C061767 for ; Thu, 24 Jun 2021 05:31:25 -0700 (PDT) Received: by mail-lj1-x22c.google.com with SMTP id z22so7496626ljh.8 for ; Thu, 24 Jun 2021 05:31:25 -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=ntc5rp5Qo89ApXwL9l1/cL9VK38RT4hK4RWM0GfRIGE=; b=irTXJ9/aAsEha6NU0r4G49gUv6Bco2ucKVONHHsYYZpdZDbceq49ae9chyRJAbuZrz yATeTESuhflHZh16/KtE7OFQxA37Te19oyQuC2t4WIHaHdAKlmyvTpI8rPZwCk0/hE+k KVBhbTfcbX50N+eZTDddq3vVGoXX0EU+yBd6Hqv8H2lL+TedkMq1xfR9bI4QMmsQ/qxM bT/fKz0hPxouxnvJL8G7xO3itXm8bZcsNHEOvEtGFtOW9pm57fHjBLK9fsLFAwWz/uqm h10c/gEwufecT3Yj2zCcFNIMXWsEvVNSEWxp96ZdludFvvdtl+3jCv8vaCV0v1QzJKIs xVfg== 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=ntc5rp5Qo89ApXwL9l1/cL9VK38RT4hK4RWM0GfRIGE=; b=k5k43bktqp5c/4r8wzU5gRksbsf94XHMkVpUpAeO3OfkTy+iMDfqIWRY0cUpOs5Mue TFp44hwNSSt0DIZBijkB1muX3ySJt6iThF8zjTwtgTfsS6+BOyr/lPqMYcuf4rgcx87l jF6eVfpci2Z6JBdnaNWvj7Xm0mFwDAqHv4dj3TcypYYIx9bOnrXZ2G00Lhf42Gjh/yo8 vbPLmXIHpD5eWmjQLrUCv005YqjjZAeUA/WGdJ8WeHWl7Rd86nAFEwQlkgIqa6N6EXIf mbb6EHLW6Vq6hoEGScN/Q12igOZ9782zhDvYR81xYaBxZUP7osnu4cVSp5hmJyeWVEws LRyg== X-Gm-Message-State: AOAM53377O/Vfkb74MJwnocrTZu8kJ2eCew+XsH4CmxCyXABQp1tee30 VLtOqCIWql/fBmSUo//ZY5gLQXKPMz8uO2IB2zcbSA== X-Google-Smtp-Source: ABdhPJxw3m7kanIA/XXScoeRBdjTNFdQBARRSUQJGtWpUzaeVEmGPjBwEdSn2x/HyX0Us4OWrS2JQ7u8hJrAm3JKflY= X-Received: by 2002:a2e:9a8a:: with SMTP id p10mr3746079lji.221.1624537884197; Thu, 24 Jun 2021 05:31:24 -0700 (PDT) MIME-Version: 1.0 References: <17fc60a3-cc50-7cff-eb46-904c2f0c416e@canonical.com> <20201118235015.GB6015@geo.homenetwork> <20201119003319.GA6805@geo.homenetwork> <7c9462c9-8908-8592-0727-9117d4173724@canonical.com> In-Reply-To: From: Vincent Guittot Date: Thu, 24 Jun 2021 14:31:12 +0200 Message-ID: Subject: Re: [PATCH v3] sched/fair: fix unthrottle_cfs_rq for leaf_cfs_rq list To: Po-Hsu Lin Cc: "Guilherme G. Piccoli" , Tao Zhou , "gregkh@linuxfoundation.org" , Sasha Levin , SeongJae Park , Ben Segall , Dietmar Eggemann , Juri Lelli , Tao Zhou , Mel Gorman , Ingo Molnar , Tao Zhou , Phil Auld , Peter Zijlstra , Pavan Kondeti , Steven Rostedt , Jay Vosburgh , Gavin Guo , halves@canonical.com, nivedita.singhvi@canonical.com, linux-kernel , "# v4 . 16+" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, 24 Jun 2021 at 12:29, Po-Hsu Lin wrote: > > Hello Vincent, > > sorry to resurrect this thread again, > I was trying to backport this patch and corresponding fixes to our > Ubuntu 4.15 kernel [1] to fix an issue report by LTP cfs_bandwidth01 > test[2], my colleague Guilherme told me there once a discussion about > backporting this on this thread. > > You mentioned here this should not be backported to earlier stable > kernel, I am curious if there is any specific reason of it? Too risky > maybe? Yes, IIRC there are some dependencies with other patchsets that make the backport complex and not straight forward > Thanks! > PHLin > > [1] https://lists.ubuntu.com/archives/kernel-team/2021-June/121571.html > [2] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/sched/cfs-scheduler/cfs_bandwidth01.c > > > On Thu, Nov 19, 2020 at 9:25 PM Vincent Guittot > wrote: > > > > On Thu, 19 Nov 2020 at 12:36, Guilherme G. Piccoli > > wrote: > > > > > > > > > > > > On 19/11/2020 05:36, Vincent Guittot wrote: > > > > On Thu, 19 Nov 2020 at 01:36, Tao Zhou wrote: > > > >> > > > >> On Thu, Nov 19, 2020 at 07:50:15AM +0800, Tao Zhou wrote: > > > >>> On Wed, Nov 18, 2020 at 07:56:38PM -0300, Guilherme G. Piccoli wrote: > > > >>>> Hi Vincent (and all CCed), I'm sorry to ping about such "old" patch, but > > > >>>> we experienced a similar condition to what this patch addresses; it's an > > > >>>> older kernel (4.15.x) but when suggesting the users to move to an > > > >>>> updated 5.4.x kernel, we noticed that this patch is not there, although > > > >>>> similar ones are (like [0] and [1]). > > > >>>> > > > >>>> So, I'd like to ask if there's any particular reason to not backport > > > >>>> this fix to stable kernels, specially the longterm 5.4. The main reason > > > >>>> behind the question is that the code is very complex for non-experienced > > > >>>> scheduler developers, and I'm afraid in suggesting such backport to 5.4 > > > >>>> and introduce complex-to-debug issues. > > > >>>> > > > >>>> Let me know your thoughts Vincent (and all CCed), thanks in advance. > > > >>>> Cheers, > > > >>>> > > > >>>> > > > >>>> Guilherme > > > >>>> > > > >>>> > > > >>>> P.S. For those that deleted this thread from the email client, here's a > > > >>>> link: > > > >>>> https://lore.kernel.org/lkml/20200513135528.4742-1-vincent.guittot@linaro.org/ > > > >>>> > > > >>>> > > > >>>> [0] > > > >>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe61468b2cb > > > >>>> > > > >>>> [1] > > > >>>> https://lore.kernel.org/lkml/20200506141821.GA9773@lorien.usersys.redhat.com/ > > > >>>> <- great thread BTW! > > > >>> > > > >>> 'sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list" failed to apply to > > > >>> 5.4-stable tree' > > > >>> > > > >>> You could check above. But I do not have the link about this. Can't search it > > > >>> on LKML web: https://lore.kernel.org/lkml/ > > > >>> > > > >>> BTW: 'ouwen210@hotmail.com' and 'zohooouoto@zoho.com.cn' all is myself. > > > >>> > > > >>> Sorry for the confusing.. > > > >>> > > > >>> Thanks. > > > >> > > > >> Sorry again. I forget something. It is in the stable. > > > >> > > > >> Here it is: > > > >> > > > >> https://lore.kernel.org/stable/159041776924279@kroah.com/ > > > > > > > > I think it has never been applied to stable. > > > > As you mentioned, the backport has been sent : > > > > https://lore.kernel.org/stable/20200525172709.GB7427@vingu-book/ > > > > > > > > I received another emailed in September and pointed out to the > > > > backport : https://www.spinics.net/lists/stable/msg410445.html > > > > > > > > > > > >> > > > > > > Thanks a lot Tao and Vincent! Nice to know that you already worked the > > > backport, gives much more confidence when the author does that heheh > > > > > > So, this should go to stable 5.4.y, but not 4.19.y IIUC? > > > > Yeah. they should be backported up to v5.1 but not earlier > > > > Regards, > > Vincent > > > > > Cheers, > > > > > > > > > Guilherme