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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 94207C04A68 for ; Thu, 28 Jul 2022 15:35:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231164AbiG1Pfi (ORCPT ); Thu, 28 Jul 2022 11:35:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229449AbiG1Pff (ORCPT ); Thu, 28 Jul 2022 11:35:35 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 70D2B20F66 for ; Thu, 28 Jul 2022 08:35:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1659022533; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=x2lk2hqDKcE3DDLOhqbpwiGyywL02+HBUzoqQOKIEfY=; b=iCb5vOn5wMdFQEJyCuwcxsij+ENGJzjsShHIrtCq51UbVEWpUvb/+PXU2CvyME+GjjnSse Mc/bGkzZSWo8iYbuNUl4+V0mhZpH3/3klJlwe9DaDIUGVtc9LyxAv++dSoqlIwyUFT4/jS h+0GeorFyY017SFid/rwWmdO7s99eLU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-557-PA64DZPlMt2YhMyv00gn8g-1; Thu, 28 Jul 2022 11:35:28 -0400 X-MC-Unique: PA64DZPlMt2YhMyv00gn8g-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1473E8037B5; Thu, 28 Jul 2022 15:35:28 +0000 (UTC) Received: from [10.22.9.86] (unknown [10.22.9.86]) by smtp.corp.redhat.com (Postfix) with ESMTP id 91DDB2166B26; Thu, 28 Jul 2022 15:35:26 +0000 (UTC) Message-ID: Date: Thu, 28 Jul 2022 11:35:26 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH 1/2] cgroup/cpuset: Keep current cpus list if cpus affinity was explicitly set Content-Language: en-US To: =?UTF-8?Q?Michal_Koutn=c3=bd?= Cc: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , Tejun Heo , Zefan Li , Johannes Weiner , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220728005815.1715522-1-longman@redhat.com> <20220728144420.GA27407@blackbody.suse.cz> <20220728152355.GB25894@blackbody.suse.cz> From: Waiman Long In-Reply-To: <20220728152355.GB25894@blackbody.suse.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/28/22 11:23, Michal Koutný wrote: > On Thu, Jul 28, 2022 at 10:59:01AM -0400, Waiman Long wrote: >> Cgroup v1 doesn't have this problem. > v1 analogy would be: > > echo 2-3 >$dst/cpuset.cpus > # job runs in $dst > # one task T in $dst sets affinity just to one cpu > # I rethink my config, I want to allow $dst more space > echo 2-5 >$dst/cpuset.cpus > > Most tasks in $dst happily utilize the new cpus but it breaks affinity > for T -- this must have been broken since ever. > > (Or I'd argue that per-thread affinities are just recommendations, if I > have a task for nohz CPU, I should enforce its placement with cpuset > from the beginning.) I should have clarified that what I meant is systemd on a cgroup v1 environment doesn't cause this cpu list reset to happen. It doesn't mean that cgroup v1 has no similar problem. Sorry for the confusion. Cheers, Longman