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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 56887C43140 for ; Thu, 21 Jun 2018 03:09:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C8D620875 for ; Thu, 21 Jun 2018 03:09:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C8D620875 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932469AbeFUDJd (ORCPT ); Wed, 20 Jun 2018 23:09:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37576 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932385AbeFUDJb (ORCPT ); Wed, 20 Jun 2018 23:09:31 -0400 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.25]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 92E2EC03DFE7; Thu, 21 Jun 2018 03:09:30 +0000 (UTC) Received: from llong.remote.csb (ovpn-116-138.phx2.redhat.com [10.3.116.138]) by smtp.corp.redhat.com (Postfix) with ESMTP id E401E2010D5A; Thu, 21 Jun 2018 03:09:23 +0000 (UTC) Subject: Re: [PATCH v10 5/9] cpuset: Make sure that domain roots work properly with CPU hotplug To: Peter Zijlstra Cc: Tejun Heo , Li Zefan , Johannes Weiner , Ingo Molnar , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@fb.com, pjt@google.com, luto@amacapital.net, Mike Galbraith , torvalds@linux-foundation.org, Roman Gushchin , Juri Lelli , Patrick Bellasi References: <1529295249-5207-1-git-send-email-longman@redhat.com> <1529295249-5207-6-git-send-email-longman@redhat.com> <20180620141538.GJ2494@hirez.programming.kicks-ass.net> From: Waiman Long Organization: Red Hat Message-ID: Date: Thu, 21 Jun 2018 11:09:22 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20180620141538.GJ2494@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.25 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Thu, 21 Jun 2018 03:09:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/20/2018 10:15 PM, Peter Zijlstra wrote: > On Mon, Jun 18, 2018 at 12:14:04PM +0800, Waiman Long wrote: >> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst >> index 5ee5e77..6ef3516 100644 >> --- a/Documentation/admin-guide/cgroup-v2.rst >> +++ b/Documentation/admin-guide/cgroup-v2.rst >> @@ -1626,6 +1626,13 @@ Cpuset Interface Files >> 2) No CPU that has been distributed to child scheduling domain >> roots is deleted. >> >> + When all the CPUs allocated to a scheduling domain are offlined, >> + that scheduling domain will be temporaily gone and all the >> + tasks in that scheduling domain will migrate to another one that >> + belongs to the parent of the scheduling domain root. When any >> + of those offlined CPUs is onlined again, a new scheduling domain >> + will be re-created and the tasks will be migrated back. >> + > You should mention that this is a destructive operation. If any of the > tasks had an affinity smaller than the original cgroup, that will be > gone. Thanks for the information. Will update the documentation to mention that. Cheers, Longman