From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 4E72B6B003D for ; Tue, 17 Mar 2009 00:48:54 -0400 (EDT) Received: from mt1.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n2H4mqFn030784 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Tue, 17 Mar 2009 13:48:52 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id B982945DE55 for ; Tue, 17 Mar 2009 13:48:51 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 7D00645DE4E for ; Tue, 17 Mar 2009 13:48:51 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 3E6C6E08005 for ; Tue, 17 Mar 2009 13:48:51 +0900 (JST) Received: from m107.s.css.fujitsu.com (m107.s.css.fujitsu.com [10.249.87.107]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id E576C1DB803C for ; Tue, 17 Mar 2009 13:48:50 +0900 (JST) Date: Tue, 17 Mar 2009 13:47:27 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH 4/4] Memory controller soft limit reclaim on contention (v6) Message-Id: <20090317134727.62efc14e.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090317044016.GG16897@balbir.in.ibm.com> References: <20090316095258.94ae559d.kamezawa.hiroyu@jp.fujitsu.com> <20090316083512.GV16897@balbir.in.ibm.com> <20090316174943.53ec8196.kamezawa.hiroyu@jp.fujitsu.com> <20090316180308.6be6b8a2.kamezawa.hiroyu@jp.fujitsu.com> <20090316091024.GX16897@balbir.in.ibm.com> <2217159d612e4e4d3fcbd50354e53f5b.squirrel@webmail-b.css.fujitsu.com> <20090316113853.GA16897@balbir.in.ibm.com> <969730ee419be9fbe4aca3ec3249650e.squirrel@webmail-b.css.fujitsu.com> <20090316121915.GB16897@balbir.in.ibm.com> <20090317124740.d8356d01.kamezawa.hiroyu@jp.fujitsu.com> <20090317044016.GG16897@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: linux-mm@kvack.org, YAMAMOTO Takashi , lizf@cn.fujitsu.com, KOSAKI Motohiro , Rik van Riel , Andrew Morton List-ID: On Tue, 17 Mar 2009 10:10:16 +0530 Balbir Singh wrote: > > - vm.softlimit_ratio > > > > If vm.softlimit_ratio = 99%, > > when sum of all usage of memcg is over 99% of system memory, > > softlimit runs and reclaim memory until the whole usage will be below 99%. > > (or some other trigger can be considered.) > > > > Then, > > - We don't have to take care of misc. complicated aspects of memory reclaiming > > We reclaim memory based on our own logic, then, no influence to global LRU. > > > > I think this approach will hide the all corner case and make merging softlimit > > to mainline much easier. If you use this approach, RB-tree is the best one > > to go with (and we don't have to care zone's status.) > > I like the idea in general, but I have concerns about > > 1. Tracking all cgroup memory, it can quickly get expensive (tracking > to check for vm.soft_limit_ratio and for usage) Not so expensive because we already tracks them all by default cgroup. Then, what we need is "fast" counter. Maybe percpu coutner (lib/percpu_counter.c) gives us enough codes for counting. Checking value ratio is ...how about "once per 1000 increment per cpu" or some ? > 2. Finding a good default for the sysctl (might not be so hard) > I think some parameter like high-low watermark is good and we can find good value as - low watermak .... max_memory - (sum of all zone->high) * 16 of memory. - high watermark .... max_memory - (sum_of all zone->high) * 8 (just an example but not so bad.) > Even today our influence on global LRU is very limited, only when we > come under reclaim, we do an additional step of seeing if we can get > memory from soft limit groups first. > > (1) is a real concern. Maybe yes. But all memcg will call "charge" "uncharge" codes so, problem is just "counter". I think percpu coutner works enough. Thanks, -Kame -- 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/ . Don't email: email@kvack.org