This appendix provides an overview of the mapping of tasks for the Blue Gene/Q system.
Mapping is defined as the assignment of processes to Blue Gene processors. The term MPI rank denotes a process, but the concept applies whether MPI or some other communication protocol is used. The network topology for Blue Gene/Q is a five-dimensional (5D) torus or mesh, with direct links between the nearest neighbors in the ±A, ±B, ±C, ±D, and ±E directions. When communication involves the nearest neighbors on the torus network, a large ...