Message-ID: <4F45F1F0.2010102@cn.fujitsu.com>
Date: Thu, 23 Feb 2012 15:59:44 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: Vivek Goyal <vgoyal@redhat.com>
CC: Tejun Heo <tj@kernel.org>, containers@lists.linux-foundation.org,
        cgroups@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        Kay Sievers <kay.sievers@vrfy.org>,
        Lennart Poettering <lennart@poettering.net>,
        Frederic Weisbecker <fweisbec@gmail.com>, linux-kernel@vger.kernel.org,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFD] cgroup: about multiple hierarchies
References: <20120221211938.GE12236@google.com> <20120222163858.GB4128@redhat.com>
In-Reply-To: <20120222163858.GB4128@redhat.com>
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> Trying to make all the controllers uniform in terms of their treatment
> of cgroup hiearchy sounds like a good thing to do.

Agreed.

Apart from nesting cgroups, there're other inconsistencies.

- Some controllers disallow more than one cgroup layer. That's the new
net_prio controller, and I don't know why it's made so, but I guess
it's fine to eliminate this restriction.

- Some controllers move resource charges when a task is moved to
a different cgroup, but some don't?

- Some controllers disallow task attaching under some circumstances.
So if we have a single hierarchy with all subsystems, the chance
that attaching a task to a cgroup fails may be bigger.

> Once that is done,
> one can probably see if it is worth to put all the controllers in a
> single hierarchy.
> 
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