[Devel] Re: [PATCH v3 04/13] kmem accounting basic infrastructure

[Glauber Costa]

On 09/27/2012 04:15 PM, Michal Hocko wrote:
> On Wed 26-09-12 16:33:34, Tejun Heo wrote:
> [...]
>>>> So, this seems properly crazy to me at the similar level of
>>>> use_hierarchy fiasco.  I'm gonna NACK on this.
>>>
>>> As I said: all use cases I particularly care about are covered by a
>>> global switch.
>>>
>>> I am laying down my views because I really believe they make more sense.
>>> But at some point, of course, I'll shut up if I believe I am a lone voice.
>>>
>>> I believe it should still be good to hear from mhocko and kame, but from
>>> your point of view, would all the rest, plus the introduction of a
>>> global switch make it acceptable to you?
>>
>> The only thing I'm whining about is per-node switch + silently
>> ignoring past accounting, so if those two are solved, I think I'm
>> pretty happy with the rest.
> 
> I think that per-group "switch" is not nice as well but if we make it
> hierarchy specific (which I am proposing for quite some time) and do not
> let enable accounting for a group with tasks then we get both
> flexibility and reasonable semantic. A global switch sounds too coars to
> me and it really not necessary.
> 
> Would this work with you?
> 

How exactly would that work? AFAIK, we have a single memcg root, we
can't have multiple memcg hierarchies in a system. Am I missing something?