Messages in this thread | | | From | (Larry McVoy) | Subject | Re: Remote fork() and Parallel programming | Date | Tue, 16 Jun 1998 13:27:10 -0700 |
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: I realized that I might someday want to run my app on a 100 node cluster : insted of just my SMP system... MPI seemed to be a better (performance : wise) solution to cluster programming, although it did require non-trivial : effort to program using it at first.
Agreed on both points; though I claim that it is good for your brain to fit your computation into messages, it tends to make some other nice things happen in the design of your code.
: It seemed wiser to write my software for MPI and deal with the : difficulties and it being non-optimum on my smp system. (Although I've : never tested it, I'm sure that shared memory on a smp system is *MUCH* : faster then MPI)...
Actually, only if you don't do anything to the MPI libraries. I.e., they are doing networking through the loopback device.
SGI took the libs, gutted 'em, leaving just the interfaces, and tuned them especially for SMP machines (yeah, they can still call out to the networking ones when they need to).
They even did some VM hacking such that they could map another process' address space so that a send() turned into
find the process associated with the destination make we've already mapped the destination bcopy()
It was damn close to no more than the bcopy() cost.
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