From mboxrd@z Thu Jan 1 00:00:00 1970 From: KOSAKI Motohiro Subject: Re: [PATCH 0/3] Unmapped page cache control (v5) Date: Fri, 1 Apr 2011 22:21:26 +0900 (JST) Message-ID: <20110401222250.A894.A69D9226@jp.fujitsu.com> References: <20110401165752.A889.A69D9226@jp.fujitsu.com> <20110401131214.GS2879@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Cc: kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org, akpm@linux-foundation.org, npiggin@kernel.dk, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, cl@linux.com, kamezawa.hiroyu@jp.fujitsu.com, Mel Gorman , Minchan Kim To: balbir@linux.vnet.ibm.com Return-path: In-Reply-To: <20110401131214.GS2879@balbir.in.ibm.com> Sender: owner-linux-mm@kvack.org List-Id: kvm.vger.kernel.org > * KOSAKI Motohiro [2011-04-01 16:56:57]: > > > Hi > > > > > > 1) zone reclaim doesn't work if the system has multiple node and the > > > > workload is file cache oriented (eg file server, web server, mail server, et al). > > > > because zone recliam make some much free pages than zone->pages_min and > > > > then new page cache request consume nearest node memory and then it > > > > bring next zone reclaim. Then, memory utilization is reduced and > > > > unnecessary LRU discard is increased dramatically. > > > > > > > > SGI folks added CPUSET specific solution in past. (cpuset.memory_spread_page) > > > > But global recliam still have its issue. zone recliam is HPC workload specific > > > > feature and HPC folks has no motivation to don't use CPUSET. > > > > > > I am afraid you misread the patches and the intent. The intent to > > > explictly enable control of unmapped pages and has nothing > > > specifically to do with multiple nodes at this point. The control is > > > system wide and carefully enabled by the administrator. > > > > Hm. OK, I may misread. > > Can you please explain the reason why de-duplication feature need to selectable and > > disabled by defaut. "explicity enable" mean this feature want to spot corner case issue?? > > Yes, because given a selection of choices (including what you > mentioned in the review), it would be nice to have > this selectable. It's no good answer. :-/ Who need the feature and who shouldn't use it? It this enough valuable for enough large people? That's my question point. -- 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