From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 3A73B6B003D for ; Fri, 13 Mar 2009 02:54:14 -0400 (EDT) Received: from mt1.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n2D6sBGk006590 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Fri, 13 Mar 2009 15:54:11 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 7821A45DE50 for ; Fri, 13 Mar 2009 15:54:11 +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 56E6E45DE4F for ; Fri, 13 Mar 2009 15:54:11 +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 30B661DB803A for ; Fri, 13 Mar 2009 15:54:11 +0900 (JST) Received: from ml13.s.css.fujitsu.com (ml13.s.css.fujitsu.com [10.249.87.103]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id DB0AC1DB803C for ; Fri, 13 Mar 2009 15:54:07 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [PATCH 4/4] Memory controller soft limit reclaim on contention (v5) In-Reply-To: <20090313050740.GF16897@balbir.in.ibm.com> References: <20090313134548.AF50.A69D9226@jp.fujitsu.com> <20090313050740.GF16897@balbir.in.ibm.com> Message-Id: <20090313145032.AF4D.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Fri, 13 Mar 2009 15:54:03 +0900 (JST) Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org, YAMAMOTO Takashi , lizf@cn.fujitsu.com, Rik van Riel , Andrew Morton , KAMEZAWA Hiroyuki List-ID: > > > My point is, contention case kswapd wakeup. and kswapd reclaim by > > > global lru order before soft limit shrinking. > > > Therefore, In typical usage, mem_cgroup_soft_limit_reclaim() almost > > > don't call properly. > > > > > > soft limit shrinking should run before processing global reclaim. > > > > Do you have the reason of disliking call from kswapd ? > > > > Yes, I sent that reason out as comments to Kame's patches. kswapd or > balance_pgdat controls the zones, priority and in effect how many > pages we scan while doing reclaim. I did lots of experiments and found > that if soft limit reclaim occurred from kswapd, soft_limit_reclaim > would almost always fail and shrink_zone() would succeed, since it > looks at the whole zone and is always able to find some pages at all > priority levels. It also does not allow for targetted reclaim based on > how much we exceed the soft limit by. hm I read past discussion. so, I think we discuss many aspect at once. So, my current thinking is below, (1) if the group don't have any soft limit shrinking page, mem_cgroup_soft_limit_reclaim() spent time unnecessary. -> right. actually, past global reclaim had similar problem. then zone_is_all_unreclaimable() was introduced. maybe we can use similar technique to memcg. (2) mem_cgroup_soft_limit_reclaim() should be called from? -> under discussion. we should solve (1) at first for proper constructive discussion. (3) What's "fairness" of soft limit? -> perfectly another aspect. So, I'd like to discuss (1) at first. Although we don't kswapd shrinking, (1) is problem. -- 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