Stealth: > On Friday 12 December 2008 09:06:30 am Ondrej Sluciak wrote: > > I have one very stupid question, but I want to be sure that I am > > right. If you have 2 interconnected virtual machines running and > > let them compute some problem in parallel (using message passing > > interface - MPI), is it really a parallel computation? I mean, > > when the host machine has only one core and both VMs use the same > > memory and resources (though separated), can you talk about > > parallel computation? > > I'm asking because I did some tests with with such a setup, but I > > have noticed no improvement in speed, comparing to computation on > > one VM. Does anyone have some experience with it? Thanks. > > If you mean are you getting quicker results because you are using > multiple machines? The answer would be, no, because you are using > one machine. You are simply sharing the one machine's resources > multiple applications. The VMs are just a process running inside an > application. Each VM thinks it is a separate machine and the host > machine just simply sees an application demanding resources.
Is this also true for multi-core systems? Is every VM running on the same core, or has each VM it's own core (as long as there is still an unused available)? That way you could probably make use of your cpu's full power in certain scenarios without the need for smp in the guest. Grs, Heinz
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