[O-MPI users] Re: [Beowulf] Alternative to MPI ABI
lindahl at pathscale.com
Fri Mar 25 18:26:28 EST 2005
On Fri, Mar 25, 2005 at 05:49:13PM -0500, Jeff Squyres wrote:
> MorphMPI (or, as Patrick suggests, we need a cooler name -- PatrickMPI?
> ;-) ) is the work of 1 grad clever student (or anyone else industrious
> enough). Elapsed time: a few months.
> Making even 2 MPI implementations agree on an ABI is an enormous amount
> of work. Given that two major MPI implementations take opposite sides
> on the pointers-vs.integers for MPI handles debate (and I suspect that
> neither is willing to change), just getting them to agree on one of
> them will be a major amount of work. Then changing the internals of
> one of those MPIs to match the other is another enormous amount of work
> (death by a million cuts).
You yourself said how MPI implementers would actually implement this
without needing to change any internals: Make the C interface routines
do the same thing that F77 does today. Elapsed time: a few months,
same as MorphMPI. No internals need to be changed.
I suppose the good news is that if this is your main objection,
then it's gone.
> Also, as I pointed out in my original alternate proposal, with
> PatrickMPI, only those who want to use an ABI will use it. Those who
> do *not* want an ABI do not have to have it forced upon them.
I missed where anyone was being forced to do anything. MPI
implementers can support the ABI alongside their current interface or
not, it's their choice.
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