Date: Thu, 23 Feb 2012 15:32:41 -0500
From: Vivek Goyal <vgoyal@redhat.com>
To: Li Zefan <lizf@cn.fujitsu.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
Message-ID: <20120223203241.GJ19691@redhat.com>
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On Thu, Feb 23, 2012 at 03:59:44PM +0800, Li Zefan wrote:
> > 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.

You mean don't allow creating deeper levels in cgroup hierarcy? That will
fail with libvirt + systemd as they create much deeper levels. I had to
change that for blkio.

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

I think in case of some controllers it does not even apply. For cpu, blkio
resources are renewable, so there is no moving around of charges.

Thanks
Vivek
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