[Beowulf] Alternative to MPI ABI

[Greg Lindahl]

On Fri, Mar 25, 2005 at 06:03:15PM -0500, Patrick Geoffray wrote:

> What Jeff thought is a nightmare, I believe, is to have to decide a 
> common interface and then force the MPI implementations to adopt this 
> interface internally instead of having them translating on the fly.

Ah. But no one ever suggested that, so we're all set -- it's an
artifact of the poor communication content of PowerPoint slides that
anyone thought I had suggested altering everyone's internals.

> > something?  Does this somehow save a significant amount of work for
> > anyone?
> 
> It does not, but the pill is much easier to swallow because nobody has 
> to fight to try to impose the interface they happen to use. Am I still 
> drunk and missing something big ?

If I understand it correctly, MorphMPI imposes the same interface as
an ABI -- a common mpi.h. The only thing it avoids is having a shared
library with a common name and interface; instead it will have a
separate routine per MPI implementation that dlopens all the
appropriate libs for the implementation in use, with the usual chaos
of trying to find where they are located.

In any case, I think this sort of discussion is more of an
implementation detail than a fundamental thing that would obviate
having an ABI... either way you're going to want to pick the right
contents for mpi.h. Apple or Orange, it's the same committee process.

-- greg