Re: Why do the mpi packages depend on rsh, etc?
Greetings!
Jose Marin <jose@ma.hw.ac.uk> writes:
> On Fri, 3 Mar 2000, Mark Brown wrote:
>
> > MPICH is hard-coded to use /usr/bin/rsh, although it is not particularly
> > concerned about what's there and could probably be modified relatively
> > easily. It's certainly trivial to do at compile time. As far as I
> > remember, the upstream authors take the view that the performance of ssh
> > is such that you probably don't want to use it in HPC applications.
>
> But isn't it the case that the ssh connection is only used to execute
> shell commands, and that once they're started the mpi binaries do all
> their communications independently of the rsh/ssh connection? (i.e. no
> encryption on the SEND(), RECV(), etc.)
>
> In other words, one may see a slower start-up of the application, but once
> it's running you shouldn't see any difference (unless you do a lot of i/o
> to stdout, but why would you?)
>
I think you're right here, judging from the netstat port numbers
pertaining to my running Beowulf process. But, as you note, there is
a difference at startup, possibly also with standard output.
Take care,
> Jose
> --
> Jose L Marin jose@ma.hw.ac.uk
> Dept of Mathematics marin@posta.unizar.es
> Heriot-Watt University
> Edinburgh EH14 4AS, U.K.
> Phone: +44 131 451 3893
> Fax: +44 131 451 3249
>
>
> --
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--
Camm Maguire camm@enhanced.com
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