[O-MPI users] Re: [Beowulf] Alternative to MPI ABI

Mark Hahn hahn at physics.mcmaster.ca
Sun Apr 3 17:14:04 PDT 2005

> If there is an ABI then we have a fighting chance at focusing on the 
> applications and not the ever-so-slightly-strange version of whichever 
> flavor of MPI that they chose to use.

wonderful!  yes: ABI standards are good and proprietary
implementations (which inherently provide only negative 
definitions of support) are bad.

after all, the real appeal is that N MPI implementation only need to test
their own conformity to the standard, and M applications test their
conformity.  ie, N+M tests, rather than N*M without an ABI.  this 
assumes that the ABI/standard is broad enough, of course!

first, it's worth asking whether there is something to be lost
by going to an ABI?  yes, dynamic linking imposes some overhead - 
I have to wonder whether some of the higher-performing interconnects
(SGI/Cray/Quadrics/Pathscale) are low-latency enough to worry about 
indirect library calls blowing the pipeline.

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