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Re: [Xen-devel] xen and virtual iron

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

It seems like most of the tricky work is around caching to optimize the
performance across the slower communication bus (when sharing between
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

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