[Pkg-openmpi-maintainers] preferred MPI: openmpi or mpich?

[Michael Banck]

Hi,

We (Debichem) also have a few upstreams that claim OpenMPI is more buggy
than MPICH.

Of course, that mustn't be the case by the time buster is released.

On Fri, Jul 07, 2017 at 09:22:52AM +0100, Alastair McKinstry wrote:
> The bigger question here is : how do we decide between them?

How about we have both, at least for the core linear algebra packages,
like scalapack etc.?

> At $work when we make the decision on default MPI to recommend when we
> install a new cluster, testing our standard codes and benchmarking:
> first does it compile and work (nearly always), secondly whats the speed
> / latency / variance?
> 
> Given our user base, the most useful criteria is probably: does it have
> the necessary feature base. We can't benchmark as we don't know general
> users' hardware.  OpenMPI appears to have more complete hardware
> support, and should be the default unless it is shown to be 'too buggy'.
> 
> How to test ? can we go through our package base and turn on MPI
> threading in testing?
 
There's http://packages.debian.org/src:mpi-testsuite which is basically
the MPICH testsuite, but OpenMPI runs on it as well.  The idea was to
see how the various implementation work on the various architectures.

I haven't worked on that package in a while and/or analysed the results,
so if somebody want to help/take it from here, be my guest.


Michael