From: Michal Hocko <mhocko@suse.cz>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>
Subject: Re: [PATCH v4 3/5] memcg : stop scanning if enough
Date: Mon, 1 Aug 2011 21:49:42 +0200 [thread overview]
Message-ID: <20110801194905.GA5354@tiehlicka.suse.cz> (raw)
In-Reply-To: <20110801143745.GF25251@tiehlicka.suse.cz>
On Mon 01-08-11 16:37:45, Michal Hocko wrote:
> On Wed 27-07-11 14:49:00, KAMEZAWA Hiroyuki wrote:
> > memcg :avoid node fallback scan if possible.
> >
> > Now, try_to_free_pages() scans all zonelist because the page allocator
> > should visit all zonelists...but that behavior is harmful for memcg.
> > Memcg just scans memory because it hits limit...no memory shortage
> > in pased zonelist.
> >
> > For example, with following unbalanced nodes
> >
> > Node 0 Node 1
> > File 1G 0
> > Anon 200M 200M
> >
> > memcg will cause swap-out from Node1 at every vmscan.
> >
> > Another example, assume 1024 nodes system.
> > With 1024 node system, memcg will visit 1024 nodes
> > pages per vmscan... This is overkilling.
> >
> > This is why memcg's victim node selection logic doesn't work
> > as expected.
>
> Previous patch adds nodemask filled by
> mem_cgroup_select_victim_node. Shouldn't we rather limit that nodemask
> to a victim node?
Bahh, scratch that. I was jumping from one thing to another and got
totally confused. Victim memcg is not bound to any particular node in
general...
Sorry for noise. I will try to get back to this tomorrow.
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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next prev parent reply other threads:[~2011-08-01 19:49 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-27 5:44 [PATCH v4 0/5] memcg : make numa scanning better KAMEZAWA Hiroyuki
2011-07-27 5:46 ` [PATCH v4 1/5] memcg : update numascan info by schedule_work KAMEZAWA Hiroyuki
2011-07-27 5:47 ` [PATCH v4 2/5] memcg : pass scan nodemask KAMEZAWA Hiroyuki
2011-08-01 13:59 ` Michal Hocko
2011-08-02 2:21 ` KAMEZAWA Hiroyuki
2011-07-27 5:49 ` [PATCH v4 3/5] memcg : stop scanning if enough KAMEZAWA Hiroyuki
2011-08-01 14:37 ` Michal Hocko
2011-08-01 19:49 ` Michal Hocko [this message]
2011-07-27 5:49 ` [PATCH v4 4/5] memcg : calculate node scan weight KAMEZAWA Hiroyuki
2011-07-27 5:51 ` [PATCH v4 5/5] memcg : select a victim node by weights KAMEZAWA Hiroyuki
2011-07-27 5:52 ` [PATCH v4 6/5] memcg : check numa balance KAMEZAWA Hiroyuki
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