From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759704AbZDQLf3 (ORCPT ); Fri, 17 Apr 2009 07:35:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757709AbZDQLfU (ORCPT ); Fri, 17 Apr 2009 07:35:20 -0400 Received: from serv2.oss.ntt.co.jp ([222.151.198.100]:53718 "EHLO serv2.oss.ntt.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757436AbZDQLfT (ORCPT ); Fri, 17 Apr 2009 07:35:19 -0400 Message-ID: <49E86975.1030200@oss.ntt.co.jp> Date: Fri, 17 Apr 2009 20:35:17 +0900 From: =?ISO-8859-1?Q?Fernando_Luis_V=E1zquez_Cao?= User-Agent: Mozilla-Thunderbird 2.0.0.19 (X11/20090103) MIME-Version: 1.0 To: Li Zefan , KAMEZAWA Hiroyuki , Paul Menage , Balbir Singh , Gui Jianfeng , agk@sourceware.org, akpm@linux-foundation.org, axboe@kernel.dk, baramsori72@gmail.com, Carl Henrik Lunde , dave@linux.vnet.ibm.com, Divyesh Shah , eric.rannaud@gmail.com, fernando@oss.ntt.co.jp, Hirokazu Takahashi , matt@bluehost.com, dradford@bluehost.com, ngupta@google.com, randy.dunlap@oracle.com, roberto@unbit.it, Ryo Tsuruta , Satoshi UCHIDA , subrata@linux.vnet.ibm.com, yoshikawa.takuya@oss.ntt.co.jp, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/9] io-throttle documentation References: <1239740480-28125-1-git-send-email-righi.andrea@gmail.com> <1239740480-28125-2-git-send-email-righi.andrea@gmail.com> <20090417102417.88a0ef93.kamezawa.hiroyu@jp.fujitsu.com> <49E7E1CF.6060209@cn.fujitsu.com> <20090417102539.GA16838@linux> In-Reply-To: <20090417102539.GA16838@linux> 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 Andrea Righi wrote: > On Fri, Apr 17, 2009 at 09:56:31AM +0800, Li Zefan wrote: >> KAMEZAWA Hiroyuki wrote: >>> On Tue, 14 Apr 2009 22:21:12 +0200 >>> Andrea Righi wrote: >>> >>>> +Example: >>>> +* Create an association between an io-throttle group and a bio-cgroup group >>>> + with "bio" and "blockio" subsystems mounted in different mount points: >>>> + # mount -t cgroup -o bio bio-cgroup /mnt/bio-cgroup/ >>>> + # cd /mnt/bio-cgroup/ >>>> + # mkdir bio-grp >>>> + # cat bio-grp/bio.id >>>> + 1 >>>> + # mount -t cgroup -o blockio blockio /mnt/io-throttle >>>> + # cd /mnt/io-throttle >>>> + # mkdir foo >>>> + # echo 1 > foo/blockio.bio_id >>> Why do we need multiple cgroups at once to track I/O ? >>> Seems complicated to me. >>> >> IIUC, it also disallows other subsystems to be binded with blockio subsys: >> # mount -t cgroup -o blockio cpuset xxx /mnt >> (failed) >> >> and if a task is moved from cg1(id=1) to cg2(id=2) in bio subsys, this task >> will be moved from CG1(id=1) to CG2(id=2) automatically in blockio subsys. >> >> All these are odd, unexpected, complex and bug-prone I think.. > > Implementing bio-cgroup functionality as pure infrastructure framework > instead of a cgroup subsystem would remove all this oddity and > complexity. Andrea, I agree with you completely. In fact, we have been working on that for a while and have just proposed doing exactly that on a different mail thread (you are CC'ed). It would be great if you could comment on that proposal. Thanks, Fernando > For example, the actual functionality that I need for the io-throttle > controller is just an interface to set and get the cgroup owner of a > page. I think it should be the same also for other potential users of > bio-cgroup. > > So, what about implementing the bio-cgroup functionality as cgroup "page > tracking" infrastructure and provide the following interfaces: > > /* > * Encode the cgrp->css.id in page_group->flags > */ > void set_cgroup_page_owner(struct page *page, struct cgroup *cgrp); > > /* > * Returns the cgroup owner of a page, decoding the cgroup id from > * page_cgroup->flags. > */ > struct cgroup *get_cgroup_page_owner(struct page *page); > > This also wouldn't increase the size of page_cgroup because we can > encode the cgroup id in the unused bits of page_cgroup->flags, as > originally suggested by Kame. > > And I think it could be used also by dm-ioband, even if it's not a > cgroup-based subsystem... but I may be wrong. Ryo what's your opinion? > > -Andrea