From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id C1AA56B0012 for ; Thu, 16 Jun 2011 07:42:07 -0400 (EDT) Date: Thu, 16 Jun 2011 13:41:56 +0200 From: Michal Hocko Subject: Re: [patch 4/8] memcg: rework soft limit reclaim Message-ID: <20110616114156.GE9840@tiehlicka.suse.cz> References: <1306909519-7286-1-git-send-email-hannes@cmpxchg.org> <1306909519-7286-5-git-send-email-hannes@cmpxchg.org> <20110609150026.GD3994@tiehlicka.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Ying Han Cc: Johannes Weiner , KAMEZAWA Hiroyuki , Daisuke Nishimura , Balbir Singh , Andrew Morton , Rik van Riel , Minchan Kim , KOSAKI Motohiro , Mel Gorman , Greg Thelen , Michel Lespinasse , "linux-mm@kvack.org" , linux-kernel On Wed 15-06-11 15:48:25, Ying Han wrote: > On Thu, Jun 9, 2011 at 8:00 AM, Michal Hocko wrote: > > On Thu 02-06-11 22:25:29, Ying Han wrote: [...] > > yes, this makes sense but I am not sure about the right(tm) value of the > > MEMCG_SOFTLIMIT_RECLAIM_PRIORITY. 2 sounds too low. You would do quite a > > lot of loops > > (DEFAULT_PRIORITY-MEMCG_SOFTLIMIT_RECLAIM_PRIORITY) * zones * memcg_count > > without any progress (assuming that all of them are under soft limit > > which doesn't sound like a totally artificial configuration) until you > > allow reclaiming from groups that are under soft limit. Then, when you > > finally get to reclaiming, you scan rather aggressively. > > Fair enough, something smarter is definitely needed :) > > > > > Maybe something like 3/4 of DEFAULT_PRIORITY? You would get 3 times > > over all (unbalanced) zones and all cgroups that are above the limit > > (scanning max{1/4096+1/2048+1/1024, 3*SWAP_CLUSTER_MAX} of the LRUs for > > each cgroup) which could be enough to collect the low hanging fruit. > > Hmm, that sounds more reasonable than the initial proposal. > > For the same worst case where all the memcgs are blow their soft > limit, we need to scan 3 times of total memcgs before actually doing it is not scanning what we do. We just walk through all existing memcgs. I think that the real issue here is how much we scan when we start doing something useful. Maybe even DEFAULT_PRIORITY-3 is too much as well. dunno. -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- 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