Date: Thu, 7 Jun 2012 12:26:10 +0200
From: Frederic Weisbecker <fweisbec@gmail.com>
To: Glauber Costa <glommer@parallels.com>
Cc: linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org,
        kamezawa.hiroyu@jp.fujitsu.com, Tejun Heo <tj@kernel.org>,
        Li Zefan <lizefan@huawei.com>, Greg Thelen <gthelen@google.com>,
        Suleiman Souhlal <suleiman@google.com>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>, devel@openvz.org,
        David Rientjes <rientjes@google.com>
Subject: Re: [PATCH v3 00/28] kmem limitation for memcg
Message-ID: <20120607102604.GE19842@somewhere.redhat.com>
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On Fri, May 25, 2012 at 05:03:20PM +0400, Glauber Costa wrote:
> Hello All,
> 
> This is my new take for the memcg kmem accounting. This should merge
> all of the previous comments from you, plus fix a bunch of bugs.
> 
> At this point, I consider the series pretty mature. Since last submission
> 2 weeks ago, I focused on broadening the testing coverage. Some bugs were
> fixed, but that of course doesn't mean no bugs exist.
> 
> I believe some of the early patches here are already in some trees around.
> I don't know who should pick this, so if everyone agrees with what's in here,
> please just ack them and tell me which tree I should aim for (-mm? Hocko's?)
> and I'll rebase it.
> 
> I should point out again that most, if not all, of the code in the caches
> are wrapped in static_key areas, meaning they will be completely patched out
> until the first limit is set. Enabling and disabling of static_keys incorporate
> the last fixes for sock memcg, and should be pretty robust.
> 
> I also put a lot of effort, as you will all see, in the proper separation
> of the patches, so the review process is made as easy as the complexity of
> the work allows to.

So I believe that if I want to implement a per kernel stack accounting/limitation,
I need to work on top of your patchset.

What do you think about having some sub kmem accounting based on the caches?
For example there could be a specific accounting per kmem cache.

Like if we use a specific kmem cache to allocate the kernel stack
(as is done by some archs but I can generalize that for those who want
kernel stack accounting), allocations are accounted globally in the memcg as
done in your patchset but also on a seperate counter only for this kmem cache
on the memcg, resulting in a kmem.stack.usage somewhere.

The concept of per kmem cache accounting can be expanded more for any
kind of finegrained kmem accounting.

Thoughts?
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