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Date: Mon, 24 Sep 2012 12:12:23 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Tejun Heo <tj@kernel.org>
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        <kamezawa.hiroyu@jp.fujitsu.com>, <devel@openvz.org>,
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        Pekka Enberg <penberg@cs.helsinki.fi>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache
References: <1347977530-29755-1-git-send-email-glommer@parallels.com> <1347977530-29755-6-git-send-email-glommer@parallels.com> <20120921181458.GG7264@google.com>
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On 09/21/2012 10:14 PM, Tejun Heo wrote:
> Hello, Glauber.
> 
> On Tue, Sep 18, 2012 at 06:11:59PM +0400, Glauber Costa wrote:
>> +void memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *cachep)
>> +{
>> +	int id = -1;
>> +
>> +	if (!memcg)
>> +		id = ida_simple_get(&cache_types, 0, MAX_KMEM_CACHE_TYPES,
>> +				    GFP_KERNEL);
>> +	cachep->memcg_params.id = id;
>> +}
> 
> I'm a bit confused.  Why is id allocated only when memcg is NULL?
> 

I think you figured that out already from your answer in another patch,
right? But I'll add a comment here since it seems to be a a natural
search point for people, explaining the mechanism.

> Also, how would the per-memcg slab/slubs appear in slabinfo?  If they
> appear separately it might be better to give them readable cgroup
> names.
>

The new caches will appear under /proc/slabinfo with the rest, with a
string appended that identifies the group.

> Thanks.
>