From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 899266B0156 for ; Mon, 15 Mar 2010 14:48:57 -0400 (EDT) Received: by pvg2 with SMTP id 2so733967pvg.14 for ; Mon, 15 Mar 2010 11:48:52 -0700 (PDT) Message-ID: <4B9E810E.9010706@codemonkey.ws> Date: Mon, 15 Mar 2010 13:48:46 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [PATCH][RF C/T/D] Unmapped page cache control - via boot parameter References: <20100315072214.GA18054@balbir.in.ibm.com> <4B9DE635.8030208@redhat.com> <20100315080726.GB18054@balbir.in.ibm.com> <4B9DEF81.6020802@redhat.com> <20100315091720.GC18054@balbir.in.ibm.com> <4B9DFD9C.8030608@redhat.com> In-Reply-To: <4B9DFD9C.8030608@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Avi Kivity Cc: balbir@linux.vnet.ibm.com, KVM development list , Rik van Riel , KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" List-ID: On 03/15/2010 04:27 AM, Avi Kivity wrote: > > That's only beneficial if the cache is shared. Otherwise, you could > use the balloon to evict cache when memory is tight. > > Shared cache is mostly a desktop thing where users run similar > workloads. For servers, it's much less likely. So a modified-guest > doesn't help a lot here. Not really. In many cloud environments, there's a set of common images that are instantiated on each node. Usually this is because you're running a horizontally scalable application or because you're supporting an ephemeral storage model. In fact, with ephemeral storage, you typically want to use cache=writeback since you aren't providing data guarantees across shutdown/failure. Regards, Anthony Liguori -- 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