From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 99BDC8D0040 for ; Fri, 1 Apr 2011 14:06:38 -0400 (EDT) Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.31.245]) by e23smtp03.au.ibm.com (8.14.4/8.13.1) with ESMTP id p31I0Kun020272 for ; Sat, 2 Apr 2011 05:00:20 +1100 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p31I53Sm1347668 for ; Sat, 2 Apr 2011 05:05:03 +1100 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p31I52Ls028247 for ; Sat, 2 Apr 2011 05:05:03 +1100 Date: Fri, 1 Apr 2011 23:34:55 +0530 From: Balbir Singh Subject: Re: [PATCH 0/3] Unmapped page cache control (v5) Message-ID: <20110401180455.GU2879@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20110401165752.A889.A69D9226@jp.fujitsu.com> <20110401131214.GS2879@balbir.in.ibm.com> <20110401222250.A894.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20110401222250.A894.A69D9226@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: 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 * KOSAKI Motohiro [2011-04-01 22:21:26]: > > * 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. :-/ I am afraid I cannot please you with my answers > Who need the feature and who shouldn't use it? It this enough valuable for enough large > people? That's my question point. > You can see the use cases documented, including when running Linux as a guest under other hypervisors, today we have a choice of not using host page cache with cache=none, but nothing the other way round. There are other use cases for embedded folks (in terms of controlling unmapped page cache), please see previous discussions. -- Three Cheers, 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org