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Date: Tue, 4 Sep 2012 16:35:52 +0200
From: Michal Hocko <mhocko@suse.cz>
Subject: Re: [PATCH v2] memcg: first step towards hierarchical controller
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To: Glauber Costa <glommer@parallels.com>
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Dave Jones <davej@redhat.com>, Ben Hutchings <ben@decadent.org.uk>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Paul Turner <pjt@google.com>, Lennart Poettering <lennart@poettering.net>, Kay Sievers <kay.sievers@vrfy.org>, Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>

On Tue 04-09-12 17:27:20, Glauber Costa wrote:
> On 09/04/2012 05:09 PM, Michal Hocko wrote:
> > Not really. Do it slowly means that somebody actually _notices_ that
> > something is about to change and they have a lot of time for that. This
> > will be really hard with the config option saying N by default.  People
> > will ignore that until it's too late.
> > We are interested in those users who would keep the config default N and
> > they are (ab)using use_hierarchy=0 in a way which is hard/impossible to
> > fix. This is where distributions might help and they should IMHO but why
> > to put an additional code into upstream? Isn't it sufficient that those
> > who would like to help (and take the risk) would just take the patch?
> 
> At least Fedora, seem to frown upon heavily at non-upstream patches.

OK, so what about the following approach instead? We won't change the
default but rather shout at people when they actually create subtrees
with use_hierarchy==0. This shouldn't make pointless noise. I do not
remember whether we have considered this previously so sorry if this was
shot down as well.
---