From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v10 5/9] cpuset: Make sure that domain roots work properly with CPU hotplug Date: Wed, 20 Jun 2018 16:15:38 +0200 Message-ID: <20180620141538.GJ2494@hirez.programming.kicks-ass.net> References: <1529295249-5207-1-git-send-email-longman@redhat.com> <1529295249-5207-6-git-send-email-longman@redhat.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FxjwbLB5V2s0tONoFTCK0nUFgqrtYJ0tDIalXSPoimU=; b=U1VcqErjcRcruXYokbrgi68/b 1ufxFjeNhBcrK6Cq8f3gBFpcSzQHkhDmYPod1hYZRqj4oQx3qsgyxqkoQaE6h+9ghrKcAtcLXHMXw KpCfp6y0SpMWWPAoLT+FoX7uo04UojbhBBvydaTdW8s62U/gdyV3nYqApG4eGEaOQPZ6ja1XLPzrH bUZqq1uAA8LlkY2vwMkF9ZGixgqLrMXjIBuR6Nb3BsmFpBa3LkQYq+EYy3qJ/2o3iqkc8NkUDskAr iGf9krJdwYcRccC/1qxkTofZByl4wv4Q6LxFKydyfOkfpxENdz2bkmAeobYaTgoSfy3jTq+WnwaLM Content-Disposition: inline In-Reply-To: <1529295249-5207-6-git-send-email-longman@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Waiman Long 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 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.