From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: Re: [PATCH] linux/balloon: don't allow ballooningdowna domain below a reasonable limit Date: Fri, 2 May 2008 00:03:10 +0100 Message-ID: <20080502000310.361b9c99@core> References: <20080501105958328.00000002360@djm-pc> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: "dan.magenheimer@oracle.com" , "xen-devel@lists.xensource.com" , Ky Srinivasan , Jan Beulich , KurtGarloff List-Id: xen-devel@lists.xenproject.org > It might be the case though that, in practice, vm_committed_space is a > reasonable predictor for working set for some common types of workload. Many > applications probably keep their heaps fairly warm and hence in main memory. I am dubious. What vm_committed_space does allow you to do however if you watch it in Xen is to actually ensure you never balloon out a virtual machine to the point you make it start killing stuff off. There are better ways to measure memory pressure - sizes of the various active and inactive lists etc. OLPC has code for this and a proposed memory pressure notifier feature that they use to allow user space apps to cleanup.