From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hopwood Subject: Re: Copy-on-write memory to allow many more xenU domains per machine Date: Mon, 25 Oct 2004 19:24:28 +0100 Sender: xen-devel-admin@lists.sourceforge.net Message-ID: <417D44DC.8020301@blueyonder.co.uk> References: Reply-To: david.nospam.hopwood@blueyonder.co.uk Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: xen-devel@lists.sourceforge.net List-Id: xen-devel@lists.xenproject.org Ian Pratt wrote: >>Hello >> >>Some time ago Michael Vrable talked about copy-on-write memory to enable >>large numbers of nearly identical machines to run on the same physical >>hardware. Is this a feasible proposition? I asked a few days ago in the >>original thread, but no-one seems to have noticed. It seems to me that >>it would be a very significant feature to offer. > > It's useful for honeypots and other situations where you want > very large numbers of VMs, but isn't generally a huge win. > > When I was doing the live migration work I recorded fingerprints > of all VM pages that were on several systems, and didn't find a > whole lot of commonality between VMs. I thought the idea would be to have a 'clone' primitive that would work in a similar way to Unix fork? The clone would start off sharing all pages, although a lot of them would get copied fairly quickly. Does anyone have an idea of what proportion or number of pages in a Linux system stay constant (and are not paged out) after boot? -- David Hopwood ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl