Message-ID: <4AEF987A.5090308@cn.fujitsu.com>
Date: Tue, 03 Nov 2009 10:42:02 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: Paul Menage <menage@google.com>
CC: bblum@andrew.cmu.edu, linux-kernel@vger.kernel.org,
       Linux Containers <containers@lists.linux-foundation.org>,
       Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC][PATCH 0/3] cgroups: support for module-loadable subsystems
References: <20091102212825.GA13692@andrew.cmu.edu>	 <4AEF8F7E.1000007@cn.fujitsu.com> <6599ad830911021811n7ccf7a70y6939ac581381c22f@mail.gmail.com>
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Paul Menage wrote:
> On Mon, Nov 2, 2009 at 6:03 PM, Li Zefan <lizf@cn.fujitsu.com> wrote:
>> I doubt the value of module-loadable subsystems. A cgroup subsystem
>> is usually a kernel resource controller, and normally it needs to
>> add some hooks in some in-kernel structures and functions, which
>> makes it impossible to be a module.
> 
> Not true - as the classifier example shows, if there's already a
> framework that supports hooking loadable modules into some kernel
> system, a resource controller can be a module.
> 

True. Just reminds me a pure cfq-based io controller can be a
module too, though the io controller discussed in the mini summit
won't be a pure cfq-based one.

>> In fact, net_cls is the only subsystem that can be a module, and
>> make it a module doesn't seem to have real benefit?
> 
> Wouldn't it be just as useful as any other module-loadable classifier,
> of which there are quite a few?
> 
> It's true that net_cls is currently the only subsystem that makes
> sense to use as a module, but its existence shows that the concept
> isn't too outlandish.
> 

Yes, sounds reasonable. 
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