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 ESMTP id 6EBFA6B004F for ; Fri, 28 Aug 2009 11:07:29 -0400 (EDT) Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by e28smtp08.in.ibm.com (8.14.3/8.13.1) with ESMTP id n7SF6doC016018 for ; Fri, 28 Aug 2009 20:36:39 +0530 Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id n7SF7PJl2511042 for ; Fri, 28 Aug 2009 20:37:25 +0530 Received: from d28av05.in.ibm.com (loopback [127.0.0.1]) by d28av05.in.ibm.com (8.14.3/8.13.1/NCO v10.0 AVout) with ESMTP id n7SF7OiW030629 for ; Sat, 29 Aug 2009 01:07:24 +1000 Date: Fri, 28 Aug 2009 20:37:23 +0530 From: Balbir Singh Subject: Re: [RFC][PATCH 1/5] memcg: change for softlimit. Message-ID: <20090828150723.GQ4889@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090828132015.10a42e40.kamezawa.hiroyu@jp.fujitsu.com> <20090828132321.e4a497bb.kamezawa.hiroyu@jp.fujitsu.com> <20090828072007.GH4889@balbir.in.ibm.com> <20090828163523.e51678be.kamezawa.hiroyu@jp.fujitsu.com> <20090828132643.GM4889@balbir.in.ibm.com> <20090828144539.GN4889@balbir.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" List-ID: * KAMEZAWA Hiroyuki [2009-08-28 23:58:39]: > Balbir Singh wrote: > > * KAMEZAWA Hiroyuki [2009-08-28 > > 23:29:09]: > > > >> Balbir Singh wrote: > >> > * KAMEZAWA Hiroyuki [2009-08-28 > >> > 16:35:23]: > >> > > >> > >> >> > >> >> Current soft-limit RB-tree will be easily broken i.e. not-sorted > >> >> correctly > >> >> if used under use_hierarchy=1. > >> >> > >> > > >> > Not true, I think the sorted-ness is delayed and is seen when we pick > >> > a tree for reclaim. Think of it as being lazy :) > >> > > >> plz explain how enexpectedly unsorted RB-tree can work sanely. > >> > >> > > > > There are two checks built-in > > > > 1. In the reclaim path (we see how much to reclaim, compared to the > > soft limit) > > 2. In the dequeue path where we check if we really are over soft limit > > > that's not a point. > > > I did lot of testing with the time based approach and found no broken > > cases, I;ve been testing it with the mmotm (event based approach and I > > am yet to see a broken case so far). > > > I'm sorry if I don't understand RB-tree. > I think RB-tree is a system which can sort inputs passed by caller > one by one and will be in broken state if value of nodes changed > while it's in tree. Wrong ? > While a subtree is > 7 > / \ > 3 9 > And, by some magic, the value can be changed without extract > 7 > / \ > 13 9 > The biggest is 13. But the biggest number which will be selecte will be "9". > This cannot happen today, we keep the values the same till we update the tree. I hope that clarifies. -- Balbir -- 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