From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id D24216B0071 for ; Fri, 11 Jun 2010 00:46:44 -0400 (EDT) Received: from d03relay01.boulder.ibm.com (d03relay01.boulder.ibm.com [9.17.195.226]) by e33.co.us.ibm.com (8.14.4/8.13.1) with ESMTP id o5B4gK5f005002 for ; Thu, 10 Jun 2010 22:42:20 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay01.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id o5B4kat4174788 for ; Thu, 10 Jun 2010 22:46:36 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id o5B4kaOu029745 for ; Thu, 10 Jun 2010 22:46:36 -0600 Date: Fri, 11 Jun 2010 10:16:32 +0530 From: Balbir Singh Subject: Re: [RFC/T/D][PATCH 2/2] Linux/Guest cooperative unmapped page cache control Message-ID: <20100611044632.GD5191@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20100608155140.3749.74418.sendpatchset@L34Z31A.ibm.com> <20100608155153.3749.31669.sendpatchset@L34Z31A.ibm.com> <4C10B3AF.7020908@redhat.com> <20100610142512.GB5191@balbir.in.ibm.com> <1276214852.6437.1427.camel@nimitz> <20100611105441.ee657515.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20100611105441.ee657515.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Dave Hansen , Avi Kivity , kvm , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: * KAMEZAWA Hiroyuki [2010-06-11 10:54:41]: > On Thu, 10 Jun 2010 17:07:32 -0700 > Dave Hansen wrote: > > > On Thu, 2010-06-10 at 19:55 +0530, Balbir Singh wrote: > > > > I'm not sure victimizing unmapped cache pages is a good idea. > > > > Shouldn't page selection use the LRU for recency information instead > > > > of the cost of guest reclaim? Dropping a frequently used unmapped > > > > cache page can be more expensive than dropping an unused text page > > > > that was loaded as part of some executable's initialization and > > > > forgotten. > > > > > > We victimize the unmapped cache only if it is unused (in LRU order). > > > We don't force the issue too much. We also have free slab cache to go > > > after. > > > > Just to be clear, let's say we have a mapped page (say of /sbin/init) > > that's been unreferenced since _just_ after the system booted. We also > > have an unmapped page cache page of a file often used at runtime, say > > one from /etc/resolv.conf or /etc/passwd. > > > > Hmm. I'm not fan of estimating working set size by calculation > based on some numbers without considering history or feedback. > > Can't we use some kind of feedback algorithm as hi-low-watermark, random walk > or GA (or somehing more smart) to detect the size ? > Could you please clarify at what level you are suggesting size detection? I assume it is outside the OS, right? -- 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/ . Don't email: email@kvack.org