Messages in this thread | | | Date | Tue, 16 Jun 1998 17:24:16 -0400 (EDT) | From | <> | Subject | Re: Remote fork() and Parallel programming |
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On Mon, 15 Jun 1998, Larry McVoy wrote:
> Here's another data point: scientific programmers on SMP machines > frequently use MPI instead of shared memory. The programming model > is simple, fast, and it works. Doesn't that seem completely crazy? > Use message passing on a SMP? I wonder why they do that.
I dont know about anyone else, but I would dare to guess their feelings are like mine:
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.
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)...
It was a matter of not having to reprogram it down the road. I could deal with lower smp performance today for better cluster support tommorrow..
People like a single interface. Frankly, I feel that both choices should be available to programmers. I know how to use PVM, Shared memory, and MPI. I can pick the best one for the task.
(Btw- anyone know anyone working on parallel pov? I want to do radiosity rendering, but that breaks the course granined box-o-pixels pvm model.. I'de like to recode it using MPI so that radiosity works).
> : I've read all the DIPC code (have you ?) and I think its close to meeting > : that stated aim. > > Whether I've read it or not is completely beside the point - we are > talking about programming models, not programming model implementations. > > But yes, Alan, I've read it. I've also read and used mether, the Rice > DSM, Erlichson's DSM, SCI, to mention a few others. I've worked with > most of the national labs on clusters, had extensive discussions with > 100's of real cluster users working on real, not imagined, problems, > ranging from scientific fortran jobs, to jet engine simulations, to > market trading systems, and even parallel remote make (since that's > what I care about, of course). > > I was having these debates before Linux existed. As far as I can tell, > nothing has changed. It's the same old "shared memory is easy" claim, > which strangely enough never seems to be made by the people that are > actually working in the clustering area. > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.rutgers.edu >
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