linux-kernel - Re: [PATCH] mm, memcg: Optionally disable memcg by default using Kconfig

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Message-ID: <20150519145340.GI6203@dhcp22.suse.cz>
Date:	Tue, 19 May 2015 16:53:40 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	Mel Gorman <mgorman@...e.de>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tejun Heo <tj@...nel.org>, cgroups@...r.kernel.org
Subject: Re: [PATCH] mm, memcg: Optionally disable memcg by default using
 Kconfig

On Tue 19-05-15 10:18:07, Johannes Weiner wrote:
> CC'ing Tejun and cgroups for the generic cgroup interface part
> 
> On Tue, May 19, 2015 at 11:40:57AM +0100, Mel Gorman wrote:
[...]
> > /usr/src/linux-4.0-vanilla/mm/memcontrol.c                           6.6441   395842
> >   mem_cgroup_try_charge                                                        2.950%   175781
> 
> Ouch.  Do you have a way to get the per-instruction breakdown of this?
> This function really isn't doing much.  I'll try to reproduce it here
> too, I haven't seen such high costs with pft in the past.
> 
> >   try_charge                                                                   0.150%     8928
> >   get_mem_cgroup_from_mm                                                       0.121%     7184

Indeed! try_charge + get_mem_cgroup_from_mm which I would expect to be
the biggest consumers here are below 10% of the mem_cgroup_try_charge.
Other than that the function doesn't do much else than some flags
queries and css_put...

Do you have the full trace? Sorry for a stupid question but do inlines
from other header files get accounted to memcontrol.c?

[...]
-- 
Michal Hocko
SUSE Labs
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