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Date: Fri, 21 Sep 2012 12:41:52 +0300 (EEST)
From: Pekka Enberg <penberg@kernel.org>
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To: Glauber Costa <glommer@parallels.com>
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        cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com,
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        David Rientjes <rientjes@google.com>, Ingo Molnar <mingo@elte.hu>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH v3 09/16] sl[au]b: always get the cache from its page in
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On Fri, 21 Sep 2012, Glauber Costa wrote:
> > We should assume that most distributions enable CONFIG_MEMCG_KMEM,
> > right? Therfore, any performance impact should be dependent on whether
> > or not kmem memcg is *enabled* at runtime or not.
> > 
> > Can we use the "static key" thingy introduced by tracing folks for this?
>
> Yes.
> 
> I am already using static keys extensively in this patchset, and that is
> how I intend to handle this particular case.

Cool.

The key point here is that !CONFIG_MEMCG_KMEM should have exactly *zero* 
performance impact and CONFIG_MEMCG_KMEM disabled at runtime should have 
absolute minimal impact.

			Pekka