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Date: Tue, 2 Oct 2012 16:46:10 +0200
From: Michal Hocko <mhocko@suse.cz>
To: Glauber Costa <glommer@parallels.com>
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        kamezawa.hiroyu@jp.fujitsu.com, devel@openvz.org,
        Tejun Heo <tj@kernel.org>, linux-mm@kvack.org,
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        Pekka Enberg <penberg@cs.helsinki.fi>,
        Johannes Weiner <hannes@cmpxchg.org>
Subject: Re: [PATCH v3 05/16] consider a memcg parameter in kmem_create_cache
Message-ID: <20121002144610.GA4662@dhcp22.suse.cz>
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On Tue 18-09-12 18:11:59, Glauber Costa wrote:
> Allow a memcg parameter to be passed during cache creation.
> When the slub allocator is being used, it will only merge
> caches that belong to the same memcg.
> 
> Default function is created as a wrapper, passing NULL
> to the memcg version. We only merge caches that belong
> to the same memcg.
> 
> From the memcontrol.c side, 3 helper functions are created:
> 
> 1) memcg_css_id: because slub needs a unique cache name
>    for sysfs. Since this is visible, but not the canonical
>    location for slab data, the cache name is not used, the
>    css_id should suffice.
> 
> 2) mem_cgroup_register_cache: is responsible for assigning
>     a unique index to each cache, and other general purpose
>     setup. The index is only assigned for the root caches. All
>     others are assigned index == -1.

It would be nice to describe what is memcg_params.id intended for. There
is no usage in this patch (except for create_unique_id in slub).
I guess that by root caches you mean all default caches with
memcg==NULL, right?

[...]
-- 
Michal Hocko
SUSE Labs