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From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2005-03-25 17:49:13


On Mar 25, 2005, at 5:03 PM, Greg Lindahl wrote:

>> I don't see it that way. First, the implementations of the translation
>> layers will be done by each MPI implementations.
>
> In which case it's basically the same as doing an ABI. Or did I miss
> something? Does this somehow save a significant amount of work for
> anyone?

YES!

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).

And MPI handles is only one issue. Consider all the rest of the
issues... Elapsed time: 2 years (that's optimistic).

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.

-- 
{+} Jeff Squyres
{+} The Open MPI Project
{+} http://www.open-mpi.org/