[Beowulf] MS HPC... Oh dear...

[Joe Landman]

Ashley Pittman wrote:

> I can almost see your argument here, currently there isn't a MPI ABI and
> you think that on Windows this situation might be different?  The

My current belief is that Microsoft will create/mandate the model by
supplying the MPI.  Some standards are defined after the fact.

> technical problems of making a stable, cross ISV ABI are the same on
> Linux and Windows (possibly even slightly worse under Windows), the only
> difference being that under Linux there is a large amount of inertia in
> keeping the status quo as moving to a consistent model would break at
> least somebodies applications, under a brave new Windows world that

Which is fine (breaking of the application), as the benefits IMO far
outweigh the costs.  Simple CBA:

Cost:
	some apps will break
	some will need to be recompiled, with some minor source code adjustments

Benefits:
	will work with new hardware drivers compiled as .so/.dll linked into
the base (LAM, Scali, and others demonstrate that you can do this).

> inertia isn't there so the ISV might as well mimic the ABI of somebody
> (in this case Microsoft) from day one.

I am not advocating mimicing the Microsoft ABI.  I am advocating getting
a single MPI ABI per ISA ABI.  The question of course is, which one.

> In practise I don't think this is going to be a step forward for two
> reasons, firstly the devil is in the detail so having two different code
> bases export the same ABI might work at the compile/link level but they

Not advocating the ABIs be the same across windows/linux, so I can't
really respond to this well.  The APIs should be the same, but there are
enough platform differences that an ABI being the same across them
doesn't make sense.


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Joseph Landman, Ph.D
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