From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753153Ab1HATuD (ORCPT ); Mon, 1 Aug 2011 15:50:03 -0400 Received: from cantor2.suse.de ([195.135.220.15]:56582 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752951Ab1HATt6 (ORCPT ); Mon, 1 Aug 2011 15:49:58 -0400 Date: Mon, 1 Aug 2011 21:49:42 +0200 From: Michal Hocko To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "akpm@linux-foundation.org" , "nishimura@mxp.nes.nec.co.jp" Subject: Re: [PATCH v4 3/5] memcg : stop scanning if enough Message-ID: <20110801194905.GA5354@tiehlicka.suse.cz> References: <20110727144438.a9fdfd5b.kamezawa.hiroyu@jp.fujitsu.com> <20110727144900.503a0afe.kamezawa.hiroyu@jp.fujitsu.com> <20110801143745.GF25251@tiehlicka.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110801143745.GF25251@tiehlicka.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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