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From: Vivek Goyal <vgoyal@redhat.com>
To: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Li Zefan <lizf@cn.fujitsu.com>,
	axboe@kernel.dk, ryov@valinux.co.jp,
	Andrew Morton <akpm@linux-foundation.org>,
	menage@google.com, containers@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC] [PATCH 2/2] cgroups: blkio subsystem as module
Date: Thu, 14 Jan 2010 06:42:43 -0500	[thread overview]
Message-ID: <20100114114243.GC15559@redhat.com> (raw)
In-Reply-To: <661de9471001140132o23f44a4fjb1849d865f96d19a@mail.gmail.com>

On Thu, Jan 14, 2010 at 03:02:09PM +0530, Balbir Singh wrote:
> On Tue, Jan 12, 2010 at 5:51 AM, KAMEZAWA Hiroyuki
> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Fri, 8 Jan 2010 10:10:38 -0500
> > Vivek Goyal <vgoyal@redhat.com> wrote:
> >
> >> On Fri, Jan 08, 2010 at 12:30:21AM -0500, Ben Blum wrote:
> >> > Convert blk-cgroup to be buildable as a module
> >> >
> >> > From: Ben Blum <bblum@andrew.cmu.edu>
> >> >
> >> > This patch modifies the Block I/O cgroup subsystem to be able to be built as a
> >> > module. As the CFQ disk scheduler optionally depends on blk-cgroup, config
> >> > options in block/Kconfig, block/Kconfig.iosched, and block/blk-cgroup.h are
> >> > enhanced to support the new module dependency.
> >> >
> >>
> >> Hi Ben,
> >>
> >> I will give this patch a try.
> >>
> >> So from blk-cgroup perspective, the advantage of allowing it as module
> >> will be that we can save some memory if we are not using the controller?
> >>
> > Is "moduled" blkio cgroup safe after page-tracking by page_cgroup is
> > introduced ?
> >
> 
> My guess is it won't be, unless we start exposing page_cgroup API and
> then make the module depend on memcg.

I think I agree. When we introduce page_cgroup based page tracking, either
we need to export page_cgroup API or we can force blkio controller to
compile as in-kernel if user selects the CONFIG_PAGE_TRACKING option.

So as of now, I can't think why we should not we allow compiling blkio as
module as long as core cgroup functionality supports it safely.

Thanks
Vivek

  reply	other threads:[~2010-01-14 11:43 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-31  5:10 [PATCH v4 0/4] cgroups: support for module-loadable subsystems Ben Blum
2009-12-31  5:12 ` [PATCH v4 1/4] cgroups: revamp subsys array Ben Blum
2009-12-31  5:13 ` [PATCH v4 2/4] cgroups: subsystem module loading interface Ben Blum
2009-12-31  5:14 ` [PATCH v4 3/4] cgroups: subsystem module unloading Ben Blum
2009-12-31  5:15 ` [PATCH v4 4/4] cgroups: net_cls as module Ben Blum
2010-01-07  0:04 ` [PATCH v4 0/4] cgroups: support for module-loadable subsystems Andrew Morton
2010-01-07  1:26   ` Ben Blum
2010-01-07  3:07     ` KAMEZAWA Hiroyuki
2010-01-07  6:42       ` Li Zefan
2010-01-07  7:16         ` KAMEZAWA Hiroyuki
2010-01-07  7:48           ` Ben Blum
2010-01-07  7:51             ` KAMEZAWA Hiroyuki
2010-01-07  8:04               ` Ben Blum
2010-01-07  8:14         ` Ben Blum
2010-01-07  8:22           ` Ben Blum
2010-01-08  5:27         ` Ben Blum
2010-01-08  5:29           ` [RFC] [PATCH 1/2] cgroups: modular subsystems support for use_id Ben Blum
2010-01-08  5:30           ` [RFC] [PATCH 2/2] cgroups: blkio subsystem as module Ben Blum
2010-01-08 15:10             ` Vivek Goyal
2010-01-12  0:21               ` KAMEZAWA Hiroyuki
2010-01-14  9:32                 ` Balbir Singh
2010-01-14 11:42                   ` Vivek Goyal [this message]
2010-01-08 16:33             ` Vivek Goyal
2010-01-12 23:34               ` Ben Blum
2010-01-12 23:36                 ` [PATCH v2 1/2] cgroups: modular subsystems support for use_id Ben Blum
2010-01-12 23:37                 ` [PATCH v2 2/2] cgroups: blkio subsystem as module Ben Blum
2010-01-14  9:15                   ` Jens Axboe
2010-01-14  9:29                     ` Li Zefan

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