Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754618AbZD0Kpp (ORCPT ); Mon, 27 Apr 2009 06:45:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752706AbZD0Kpg (ORCPT ); Mon, 27 Apr 2009 06:45:36 -0400 Received: from fms-01.valinux.co.jp ([210.128.90.1]:57587 "EHLO mail.valinux.co.jp" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752647AbZD0Kpf (ORCPT ); Mon, 27 Apr 2009 06:45:35 -0400 Date: Mon, 27 Apr 2009 19:45:33 +0900 (JST) Message-Id: <20090427.194533.183037823.ryov@valinux.co.jp> To: righi.andrea@gmail.com Cc: lizf@cn.fujitsu.com, kamezawa.hiroyu@jp.fujitsu.com, menage@google.com, balbir@linux.vnet.ibm.com, guijianfeng@cn.fujitsu.com, agk@sourceware.org, akpm@linux-foundation.org, axboe@kernel.dk, baramsori72@gmail.com, chlunde@ping.uio.no, dave@linux.vnet.ibm.com, dpshah@google.com, eric.rannaud@gmail.com, fernando@oss.ntt.co.jp, taka@valinux.co.jp, matt@bluehost.com, dradford@bluehost.com, ngupta@google.com, randy.dunlap@oracle.com, roberto@unbit.it, s-uchida@ap.jp.nec.com, 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 From: Ryo Tsuruta In-Reply-To: <20090420150052.GC13307@linux> References: <20090417102539.GA16838@linux> <20090420.183815.226804723.ryov@valinux.co.jp> <20090420150052.GC13307@linux> X-Mailer: Mew version 5.2.52 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2543 Lines: 83 Hi Andrea, From: Andrea Righi Subject: Re: [PATCH 1/9] io-throttle documentation Date: Mon, 20 Apr 2009 17:00:53 +0200 > On Mon, Apr 20, 2009 at 06:38:15PM +0900, Ryo Tsuruta wrote: > > Hi Andrea, > > > > > Implementing bio-cgroup functionality as pure infrastructure framework > > > instead of a cgroup subsystem would remove all this oddity and > > > complexity. > > > > > > 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? I've come up with an idea to coexist blkio-cgroup and io-throttle. blkio-cgroup provides a function to get a cgroup with the specified ID. /* Should be called under rcu_read_lock() */ struct cgroup *blkio_cgroup_lookup(int id) { struct cgroup *cgrp; struct cgroup_subsys_state *css; if (blkio_cgroup_disabled()) return NULL; css = css_lookup(&blkio_cgroup_subsys, id); if (!css) return NULL; cgrp = css->cgroup; return cgrp; } Then io-throttle can get a struct iothrottle which belongs to the cgroup by using the above function. static struct iothrottle *iothrottle_lookup(int id) { struct cgroup *grp; struct iothrottle *iot; ... grp = blkio_cgroup_lookup(id); if (!grp) return NULL iot = cgroup_to_iothrottle(grp); ... } What do you think about this way? Thanks, Ryo Tsuruta -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/