Application topologies

Application Topologies

• In many applications, processes are arranged with a particular topology, e.g., a regular grid.
• MPI supports general application topologies by a graph in which communicating processes are connected by an arc.
• MPI also provides explicit support for Cartesian grid topologies.

  mpi_cart_create (comm_old, ndims, dims, period,
                   reorder, comm_cart, ierr)

• Periodicity in each grid direction may be specified.
• Inquiry routines transform between rank in group and location in topology
• For Cartesian topologies, row-major ordering is used for processes.