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J. Träff:
"Cartesian Collective Communication: "Advice to users", "Advice to implementers", and "Advice to Standardizers"";
Talk: University of Bordeaux, Bordeaux, France (invited); 2019-12-03.

Cartesian Collective Communication (or stencil communication) is a
restricted form of general, sparse, graph neighborhood collective
communication as known in for instance MPI. The prime charactistic of
Cartesian Collective Communication is that processes organized in a
d-dimensional torus (or mesh) all communicate with the same, relative
set of neighbors. In the talk, we discuss how Cartesian Collective
Communication can be incorporated and used in MPI, giving both "advice
to users", "advice to implementers", and "advice to standardizers".
We also present new, message-combining algorithms for efficiently
supporting Cartesian Collective alltoall and allgather Communication
(for small problems), and give of experimental results showing that
this form of sparse collective communication can be supported with a
performance advantage.