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Date: Fri, 21 Sep 2012 11:14:58 -0700
From: Tejun Heo <tj@kernel.org>
To: Glauber Costa <glommer@parallels.com>
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        kamezawa.hiroyu@jp.fujitsu.com, devel@openvz.org, linux-mm@kvack.org,
        Suleiman Souhlal <suleiman@google.com>,
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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
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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?

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.

Thanks.

-- 
tejun