From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753666AbaCJORZ (ORCPT ); Mon, 10 Mar 2014 10:17:25 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:51198 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753300AbaCJORY (ORCPT ); Mon, 10 Mar 2014 10:17:24 -0400 Message-ID: <531DC971.6020208@gopivotal.com> Date: Mon, 10 Mar 2014 14:17:21 +0000 From: Glyn Normington User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Tejun Heo CC: linux-kernel@vger.kernel.org, Li Zefan Subject: Re: [PATCH] control groups: documentation improvements References: <20140310113928.GC18700@gnimac.gopivotal.com> <20140310140724.GA25290@htj.dyndns.org> In-Reply-To: <20140310140724.GA25290@htj.dyndns.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tejun Thanks for your quick reply. Responses inline. Regards, Glyn On 10/03/2014 14:07, Tejun Heo wrote: > Hello, Glyn. > > On Mon, Mar 10, 2014 at 11:39:28AM +0000, Glyn Normington wrote: >> Clarify that each hierarchy must be associated with at least one >> subsystem. > Hmmm... but named hierarchies can exist without any controllers > attached to them. Then we missed how to create a hierarchy with no associated subsystems. The only way I can think of is to use mount, specify no subsystems on -o (which defaults to all the subsystems defined in the kernel), and run it in a kernel with no subsystems defined (which seems unlikely these days). Is that what you had in mind or is there some other way of creating a hierarchy with no subsystems attached? > >> Clarify that subsystems may be attached to multiple hierarchies, >> although this isn't very useful, and explain what happens. > And a subsystem may only be attached to a single hierarchy. Perhaps that's what should happen, but the following experiment demonstrates a subsystem being attached to two hierarchies: $ pwd /home/vagrant $ mkdir mem1 $ mkdir mem2 $ sudo su # mount -t cgroup -o memory none /home/vagrant/mem1 # mount -t cgroup -o memory none /home/vagrant/mem2 # cd mem1 # mkdir inst1 # ls inst1 cgroup.clone_children memory.failcnt ... # ls ../mem2 cgroup.clone_children inst1 memory.limit_in_bytes ... # cd inst1 # echo 1000000 > memory.limit_in_bytes # cat memory.limit_in_bytes 1003520 # cat ../../mem2/inst1/memory.limit_in_bytes 1003520 # echo $$ > tasks # cat tasks 1365 1409 # cat ../../mem2/inst1/tasks 1365 1411 > > Thanks. >