itaps-parallel Notes from today's meeting

[Devine, Karen D]

On 4/19/10 8:06 AM, "Tim Tautges" <tautges at mcs.anl.gov> wrote:
> 
> This is a good time to mention another application of multiple
> partitionings, that I've encountered in two unrelated radiation
> transfer apps now. The first partiioning is the normal domain
> decomposition over procs in one communicator. The other is a broadcast
> of that whole (subdomain) mesh over a smaller set of procs. This
> second is the discretization of the energy domain over a spatial
> subdomain. In the app, you reduce across energy groups to get element-
> wise power, then across subdomains to output or reduce to vet total
> power.
> 
> This leads me to think that a part isn't synonymous wih an instance,
> but with a communicator (or, more precisely, a commmunicator is always
> associated with a part, wih the part possibly shared betw comm's).
> Thoughts?

The iMeshP header file says "Partitions have communicators associated with
them.  These communicators can be thought of as MPI communicators."  If we
made iMesh instances == Parts, we would need to associate MPI communicators
with iMesh instances, right?   Your application would not support the
assumption of MPI_COMM_WORLD everywhere, right?