From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 045356B0012 for ; Tue, 17 May 2011 09:55:58 -0400 (EDT) Message-ID: <4DD27E62.50806@redhat.com> Date: Tue, 17 May 2011 09:55:46 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [rfc patch 4/6] memcg: reclaim statistics References: <1305212038-15445-1-git-send-email-hannes@cmpxchg.org> <1305212038-15445-5-git-send-email-hannes@cmpxchg.org> <20110516231028.GV16531@cmpxchg.org> <20110517074230.GY16531@cmpxchg.org> In-Reply-To: <20110517074230.GY16531@cmpxchg.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Ying Han , KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Michal Hocko , Andrew Morton , Minchan Kim , KOSAKI Motohiro , Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org On 05/17/2011 03:42 AM, Johannes Weiner wrote: > It does hierarchical soft limit reclaim once triggered, but I meant > that soft limits themselves have no hierarchical meaning. Say you > have the following hierarchy: > > root_mem_cgroup > > aaa bbb > > a1 a2 b1 b2 > > a1-1 > > Consider aaa and a1 had a soft limit. If global memory arose, aaa and > all its children would be pushed back with the current scheme, the one > you are proposing, and the one I am proposing. > > But now consider aaa hitting its hard limit. Regular target reclaim > will be triggered, and a1, a2, and a1-1 will be scanned equally from > hierarchical reclaim. That a1 is in excess of its soft limit is not > considered at all. > > With what I am proposing, a1 and a1-1 would be pushed back more > aggressively than a2, because a1 is in excess of its soft limit and > a1-1 is contributing to that. Ying, I think Johannes has a good point. I do not see a way to enforce the limits properly with the scheme we came up with at LSF, in the hierarchical scenario above. There may be a way, but until we think of it, I suspect it will be better to go with Johannes's scheme for now. -- All rights reversed -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org