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Message-ID: <1331659918.18960.87.camel@twins>
Subject: Re: [RFD] cgroup: about multiple hierarchies
From: Peter Zijlstra <peterz@infradead.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Li Zefan <lizf@cn.fujitsu.com>,
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        Frederic Weisbecker <fweisbec@gmail.com>, linux-kernel@vger.kernel.org,
        Michal Schmidt <mschmidt@redhat.com>
Date: Tue, 13 Mar 2012 18:31:58 +0100
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On Tue, 2012-03-13 at 18:25 +0100, Peter Zijlstra wrote:
> On Tue, 2012-03-13 at 10:10 -0400, Vivek Goyal wrote:
> > Implementing hierarchy is a pain and is expensive at run time. 
> 
> Yeah, suck it up :-)
> 
> I would really rather we mandate one implementation standard for
> controllers for the sake of consistency and uniformity. A direct result
> of doing away with the multiple hierarchy crap is that all controllers
> are co-mounted. Allowing differences like this just doesn't make any
> sense.
> 
> So either we drop full hierarchy support from all controllers or we
> deprecate and remove all non-hierarchical controllers.
> 
> I'm fine with either, but I'm not fine with with the half-arsed
> solutions proposed here.

Note that before this whole discussion I was under the impressions it
was mandated for a controller to be fully hierarchical. I'm very much
surprised people were allowed to merge incomplete controllers like that.