From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Righi Subject: Re: [PATCH 1/9] io-throttle documentation Date: Mon, 20 Apr 2009 17:00:53 +0200 Message-ID: <20090420150052.GC13307__20629.1650691584$1240240427$gmane$org@linux> References: <20090417102417.88a0ef93.kamezawa.hiroyu@jp.fujitsu.com> <49E7E1CF.6060209@cn.fujitsu.com> <20090417102539.GA16838@linux> <20090420.183815.226804723.ryov@valinux.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20090420.183815.226804723.ryov-jCdQPDEk3idL9jVzuh4AOg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Ryo Tsuruta Cc: randy.dunlap-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org, menage-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, chlunde-om2ZC0WAoZIXWF+eFR7m5Q@public.gmane.org, eric.rannaud-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, balbir-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, fernando-gVGce1chcLdL9jVzuh4AOg@public.gmane.org, dradford-cT2on/YLNlBWk0Htik3J/w@public.gmane.org, agk-9JcytcrH/bA+uJoB2kUjGw@public.gmane.org, subrata-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, matt-cT2on/YLNlBWk0Htik3J/w@public.gmane.org, roberto-5KDOxZqKugI@public.gmane.org, ngupta-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org List-Id: containers.vger.kernel.org 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 looked your page_cgroup patch in io-throttle v14, It can also be used > by dm-ioband. But I'd like to eliminate lock_page_cgroup() to minimize > overhead. I'll rearrange the bio-cgroup patch according to the functions. It would be great! Anyway, I don't think it's a trivial task to completely remove lock_page_cgroup(), especially if we decide to encode the ID in page_cgroup->flags. Thanks, -Andrea