(j3.2006) (SC22WG5.5907) 3 levels of parallelism?

[Van Snyder]

On Thu, 2017-07-06 at 17:52 +0000, Bill Long wrote:
> Intentionally. The SPMD model, used by both Fortran and MPI, has
> proved to provide the best scaling and performance in real
> distributed-memory applications. 

MPMD is also useful.  Interactive graphics are not Fortran's strong
suit.  We use PVM (for historical reasons) to communicate between our
separately-launched Fortran code instances, and between Fortran and IDL
for interactive graphics.

I don't see a way to use coarrays for MPMD, but using PVM (and MPI) are
kind of like programming in assembler.