From mboxrd@z Thu Jan  1 00:00:00 1970
From: Glauber Costa <glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org>
Subject: Re: [PATCH] fix bad behavior in use_hierarchy file
Date: Tue, 26 Jun 2012 14:31:51 +0400
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To: Michal Hocko <mhocko-AlSwsSmVLrQ@public.gmane.org>
Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Dhaval Giani <dhaval.giani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Kamezawa Hiroyuki <kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Ying Han <yinghan-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

On 06/26/2012 11:56 AM, Michal Hocko wrote:
> [Adding Ying to CC - they are using hierarchies AFAIU in their workloads]
>
> On Mon 25-06-12 13:49:08, Tejun Heo wrote:
> [...]
>> A bit of delta but is there any chance we can either deprecate
>> .use_hierarhcy or at least make it global toggle instead of subtree
>> thing?
>
> So what you are proposing is to have all subtrees of the root either
> hierarchical or not, right?
>
>> This seems needlessly complicated. :(
>
> Toggle wouldn't help much I am afraid. We would still have to
> distinguish (non)hierarchical cases. And I am not sure we can make
> everything hierarchical easily.
> Most users (from my experience) ignored use_hierarchy for some reasons
> and the end results might be really unexpected for them if they used
> deeper subtrees (which might be needed due to combination with other
> controller(s)).
>
Do we have any idea about who those users are, and how is their setup 
commonly done?

We can propose work arounds here, but not without first knowing work 
arounds to what =p

One thing that would really influence this, for instance, is whether or 
not they limit at all levels in the tree, etc.