Stealth wrote: > 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. > If anything, I would expect slower results using 2 virtual machines because of the added overhead of the second virtual machine.
I am not sure even having more then one processor or core would help, because I suspect the VirtualBox is not designed for multiprocessors or cores. One way to find out would be to open more then one vm and watch the cpu load. I do not have a second vm set up right now to test it. I do know that running with one vm, I only use one core. This is handy because it automatically limits VB's cpu usage. Mikkel -- Registered Linux User #16148 (http://counter.li.org/) _______________________________________________ vbox-users mailing list [email protected] http://vbox.innotek.de/mailman/listinfo/vbox-users
