Message-ID: <4F44EFA6.2000104@parallels.com>
Date: Wed, 22 Feb 2012 17:37:42 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Tejun Heo <tj@kernel.org>, Li Zefan <lizf@cn.fujitsu.com>,
        <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@lst.de>
Subject: Re: [RFD] cgroup: about multiple hierarchies
References: <20120221211938.GE12236@google.com> <1329917459.24994.14.camel@twins>
In-Reply-To: <1329917459.24994.14.camel@twins>
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On 02/22/2012 05:30 PM, Peter Zijlstra wrote:
> On Tue, 2012-02-21 at 13:19 -0800, Tejun Heo wrote:
>> So, I mean, I don't know.  What do other people think?  Is this a
>> unnecessary worry?  Are people generally happy with the way things
>> are?  Lennart, Kay, what do you guys think?
>
> FWIW I'm all for ripping the orthogonal hierarchy crap out, I hate it
> just about as much as you do judging from your write-up.
>
> Yes it will make some people unhappy, but I can live with that since my
> life will be easier.. :-)
>
> I'm not sure on your process hierarchy pie though, I rather like being
> able to assign tasks to cgroups of my making without having to mirror
> that in the process hierarchy.
>
> Having seen what userspace does (libvirt in particular, I've still
> managed to not get infected by the systemd crap) its utterly and
> completely insane. Now I don't think any of my machines actually still
> have libvirt on it, so I don't care if we break that either ;-)
>
> Another thing I dislike about all the cgroup crap is all the dozens of
> tiny controllers being proposed left right and center. Like WTF isn't
> the hugetlb controller part of memcg? Its all memory, right?
>
Right. But this is easy to solve.
People are usually pointing out that "Hey, but that's not how my 
controller works, I need it to be slightly different here and there".
If we agree this is a bad thing - I think it is, we can at least adopt 
as a policy not to take any patches that create another hierarchy unless 
the need is utterly demonstrated.


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