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

[Drew Parsons]

I'm curious (mainly just asking out of interest, but also to discuss
whether we're configured the best way), which MPI would people
recommend in 2017?

Debian currently recommends openmpi, via mpi-defaults.  But if I
remember the history correctly, this decision was made because at the
time openmpi built successfully over a wider set of architectures, in
particular on Debian's release architectures, while mpich failed to
build on some arches.

That criterion no longer applies: both openmpi and mpich now build
successfully on all Debian arches (except sh4, where both fail to
build).

PETSc upstream, for comparison, supports openmpi but prefers mpich,
asserting that mpich has a lot fewer bugs.

Should we consider switching mpi-defaults to mpich on all arches?

Drew