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Date: Tue, 20 Nov 2012 12:27:00 -0500
From: Johannes Weiner <hannes@cmpxchg.org>
To: David Rientjes <rientjes@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Michal Hocko <mhocko@suse.cz>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Hugh Dickins <hughd@google.com>, linux-kernel@vger.kernel.org,
        cgroups@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch] mm, memcg: avoid unnecessary function call when memcg is
 disabled
Message-ID: <20121120172700.GA21703@cmpxchg.org>
References: <alpine.DEB.2.00.1211191741060.24618@chino.kir.corp.google.com>
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On Mon, Nov 19, 2012 at 05:44:34PM -0800, David Rientjes wrote:
> While profiling numa/core v16 with cgroup_disable=memory on the command 
> line, I noticed mem_cgroup_count_vm_event() still showed up as high as 
> 0.60% in perftop.
> 
> This occurs because the function is called extremely often even when memcg 
> is disabled.
> 
> To fix this, inline the check for mem_cgroup_disabled() so we avoid the 
> unnecessary function call if memcg is disabled.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>