From: Michal Hocko <mhocko@suse.cz>
To: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Sha Zhengju <handai.szj@gmail.com>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
kamezawa.hiroyu@jp.fujitsu.com, akpm@linux-foundation.org,
hughd@google.com, gthelen@google.com,
Sha Zhengju <handai.szj@taobao.com>
Subject: Re: [PATCH V2 0/3] memcg: simply lock of page stat accounting
Date: Thu, 16 May 2013 15:28:46 +0200 [thread overview]
Message-ID: <20130516132846.GE13848@dhcp22.suse.cz> (raw)
In-Reply-To: <51946071.4030101@openvz.org>
On Thu 16-05-13 08:28:33, Konstantin Khlebnikov wrote:
> Michal Hocko wrote:
> >On Wed 15-05-13 16:35:08, Konstantin Khlebnikov wrote:
> >>Sha Zhengju wrote:
> >>>Hi,
> >>>
> >>>This is my second attempt to make memcg page stat lock simpler, the
> >>>first version: http://www.spinics.net/lists/linux-mm/msg50037.html.
> >>>
> >>>In this version I investigate the potential race conditions among
> >>>page stat, move_account, charge, uncharge and try to prove it race
> >>>safe of my proposing lock scheme. The first patch is the basis of
> >>>the patchset, so if I've made some stupid mistake please do not
> >>>hesitate to point it out.
> >>
> >>I have a provocational question. Who needs these numbers? I mean
> >>per-cgroup nr_mapped and so on.
> >
> >Well, I guess it makes some sense to know how much page cache and anon
> >memory is charged to the group. I am using that to monitor the per-group
> >memory usage. I can imagine a even better coverage - something
> >/proc/meminfo like.
> >
>
> I think page counters from lru-vectors can give enough information for that.
not for dirty and writeback data which is the next step.
> If somebody needs more detailed information there are enough ways to get it.
> Amount of mapped pages can be estimated via summing rss counters from mm-structs.
> Exact numbers can be obtained via examining /proc/pid/pagemap.
How do you find out whether given pages were charged to the group of
interest - e.g. shared data or taks that has moved from a different
group without move_at_immigrate?
> I don't think that simulating 'Mapped' line in /proc/mapfile is a worth reason
> for adding such weird stuff into the rmap code on map/unmap paths.
The accounting code is trying to be not intrusive as much as possible.
This patchset makes it more complicated without a good reason and that
is why it has been Nacked by me.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2013-05-16 13:28 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-13 5:03 Sha Zhengju
2013-05-13 5:04 ` [PATCH V2 1/3] memcg: rewrite the comment about race condition " Sha Zhengju
2013-05-13 5:05 ` [PATCH V2 2/3] memcg: alter mem_cgroup_{update,inc,dec}_page_stat() args to memcg pointer Sha Zhengju
2013-05-13 12:25 ` Michal Hocko
2013-05-14 9:00 ` Sha Zhengju
2013-05-14 9:10 ` Michal Hocko
2013-05-14 0:15 ` Kamezawa Hiroyuki
2013-05-14 9:03 ` Sha Zhengju
2013-05-13 5:05 ` [PATCH V2 3/3] memcg: simplify lock of memcg page stat account Sha Zhengju
2013-05-13 13:12 ` Michal Hocko
2013-05-13 13:38 ` Michal Hocko
2013-05-14 9:13 ` Sha Zhengju
2013-05-14 9:28 ` Michal Hocko
2013-05-14 8:35 ` Sha Zhengju
2013-05-14 0:41 ` [PATCH V2 0/3] memcg: simply lock of page stat accounting Kamezawa Hiroyuki
2013-05-14 7:13 ` Michal Hocko
2013-05-15 12:35 ` Konstantin Khlebnikov
2013-05-15 13:41 ` Michal Hocko
2013-05-16 4:28 ` Konstantin Khlebnikov
2013-05-16 13:28 ` Michal Hocko [this message]
2013-05-17 5:57 ` Konstantin Khlebnikov
2013-05-17 8:38 ` Michal Hocko
2013-05-17 10:29 ` Konstantin Khlebnikov
2013-05-17 12:53 ` Michal Hocko
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