From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Theurer Subject: Re: xen and virtual iron Date: Wed, 16 Feb 2005 09:57:49 -0600 Message-ID: <42136D7D.5000904@us.ibm.com> References: <39A29C55BDB6914698687BC15B2D2EAAE6D49D@lvp1.longworth.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: <39A29C55BDB6914698687BC15B2D2EAAE6D49D@lvp1.longworth.com> Sender: xen-devel-admin@lists.sourceforge.net Errors-To: xen-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , List-Archive: To: Sean Harper Cc: "-devel@lists.sourceforge.net" List-Id: xen-devel@lists.xenproject.org Sean Harper wrote: >At Linuxworld a company called Virtual Iron is demoing a product that, >like Xen or VMWare, can break physical machines into virtual machines. > >However, unlike Xen or VMWare, this product can also aggregate physical >machines into virtual machines. In other words, it is possible for the >user to specify that 3.5 cpus from 2 machines (2 from 1 and 1.5 from >another) be assigned to a virtual machine. When linux boots on that >virtual machine it simply looks like a 4 cpu machine (but 1 of the cpus >is slower). Presumably there is a pretty big performance penalty for >sharing across machines, which they mitigate to some extent by requiring >Infiniband. > >It seems like most of the tricky work is around caching to optimize the >performance across the slower communication bus (when sharing between >machines). > > Hmm, sounds like a NUMA system, with a relatively low throughput and high latency interconnect. Not sure if anyone would want to do this on a workload where performance matters. I suppose with a layer of abstraction like Xen, doing something like this is feasible. You could leverage the NUMA code in the linux kernel, but I would think you would need a very highly parallel workload to make this effective, and if you have that, a cluster setup would probably work just as well anyway. -Andrew Theurer ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click