Routines for constructing communicators

Constructing Communicators

• New communicator for a given group:

  mpi_comm_create (comm, group, newcomm, ierr)

  • group must be a subset of the group associated with comm.
  • must be called by all processes in comm.
• Suppose we create communicators for two subgroups. These may overlap, and so must be given different contexts. Hence, all processes in the parent group must call the create routine to ensure contexts are different.