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Re: Why do the mpi packages depend on rsh, etc?

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?)

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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