From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755674Ab2CaM4v (ORCPT ); Sat, 31 Mar 2012 08:56:51 -0400 Received: from szxga04-in.huawei.com ([58.251.152.67]:45041 "EHLO szxga04-in.huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752695Ab2CaM4p (ORCPT ); Sat, 31 Mar 2012 08:56:45 -0400 Date: Sat, 31 Mar 2012 20:56:36 +0800 From: Li Zefan Subject: Re: [PATCHSET] cgroup: cftype based file interface, take #2 In-reply-to: <20120330154246.GE28934@google.com> X-Originating-IP: [10.166.88.150] To: Tejun Heo Cc: glommer@parallels.com, lizf@cn.fujitsu.com, containers@lists.linux-foundation.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, fweisbec@gmail.com, rni@google.com, ctalbott@google.com Message-id: <4F76FF04.40007@huawei.com> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 7BIT User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:11.0) Gecko/20120312 Thunderbird/11.0 X-CFilter-Loop: Reflected References: <1332368265-21586-1-git-send-email-tj@kernel.org> <4F75AA1F.9020007@huawei.com> <20120330154246.GE28934@google.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tejun Heo wrote: > Hey, Li. > > On Fri, Mar 30, 2012 at 08:42:07PM +0800, Li Zefan wrote: >>> This patch replaces cgroup file interface with cftype based one which >>> allows dynamic additions and removals of cftype arrays whether the >>> target subsystem is attached or not. This can be used to make subsys >>> rebinding via remount work properly but I intentionally avoided doing >>> that at the moment. >> >> What's the problem with remount? > > Subsys can't be changed if any non-root cgroup exists. > Ah, this is a long-standing defect, which is documented in Doc/../cgroups.txt. It's not trivial to fix it, and I never heard someone request it to be fixed. >> and is it important enough that it should be fixed even the feature >> is marked as deprecated? > > I'm not sure. We *might* need it during multi-mount -> single-mount > transition depending on how that's implemented, so the "at the moment" > qualifier. It probably won't be fixed but I'm not fully sure. > fine. >>> This makes cgroup population simpler for controllers and will be used >>> to allow controllers to be more dynamic. e.g. blkio subsys has >>> sub-policies which may come and go while blkio subsys is attached and >>> it currently uses fixed set of files which stays blank if not in use. >> >> Dynamic cgroup files was mentioned before. The scenario in mind was blkio >> control files can be added/removed automatically as devices come and ago. >> >> So this time blkio subsystem is really going to be made more dynamic >> soon? > > Patchset already posted. > > http://thread.gmane.org/gmane.linux.kernel.cgroups/1376 > Thanks!