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 B933D8D0040 for ; Thu, 31 Mar 2011 23:24:05 -0400 (EDT) Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [202.81.31.246]) by e23smtp01.au.ibm.com (8.14.4/8.13.1) with ESMTP id p313K6rm026403 for ; Fri, 1 Apr 2011 14:20:06 +1100 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p313Nxtj2367566 for ; Fri, 1 Apr 2011 14:23:59 +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 p313NxG4031818 for ; Fri, 1 Apr 2011 14:23:59 +1100 Date: Fri, 1 Apr 2011 08:38:11 +0530 From: Balbir Singh Subject: Re: [PATCH 0/3] Unmapped page cache control (v5) Message-ID: <20110401030811.GP2879@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20110330052819.8212.1359.stgit@localhost6.localdomain6> <20110331214033.GA2904@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20110331214033.GA2904@dastard> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Chinner Cc: linux-mm@kvack.org, akpm@linux-foundation.org, npiggin@kernel.dk, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kosaki.motohiro@jp.fujitsu.com, cl@linux.com, kamezawa.hiroyu@jp.fujitsu.com * Dave Chinner [2011-04-01 08:40:33]: > On Wed, Mar 30, 2011 at 11:00:26AM +0530, Balbir Singh wrote: > > > > The following series implements page cache control, > > this is a split out version of patch 1 of version 3 of the > > page cache optimization patches posted earlier at > > Previous posting http://lwn.net/Articles/425851/ and analysis > > at http://lwn.net/Articles/419713/ > > > > Detailed Description > > ==================== > > This patch implements unmapped page cache control via preferred > > page cache reclaim. The current patch hooks into kswapd and reclaims > > page cache if the user has requested for unmapped page control. > > This is useful in the following scenario > > - In a virtualized environment with cache=writethrough, we see > > double caching - (one in the host and one in the guest). As > > we try to scale guests, cache usage across the system grows. > > The goal of this patch is to reclaim page cache when Linux is running > > as a guest and get the host to hold the page cache and manage it. > > There might be temporary duplication, but in the long run, memory > > in the guests would be used for mapped pages. > > What does this do that "cache=none" for the VMs and using the page > cache inside the guest doesn't acheive? That avoids double caching > and doesn't require any new complexity inside the host OS to > acheive... > There was a long discussion on cache=none in the first posting and the downsides/impact on throughput. Please see http://www.mail-archive.com/kvm@vger.kernel.org/msg30655.html -- 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