Tuning Rendezvous

MPI_EAGERONLY

When set to 1, the default, only the eager protocol is used. When set to 0, both eager and rendez-vous protocols are used.

MPI_RSM_RENDVSIZE

Messages communicated by remote shared memory that are greater than this size will use the rendezvous protocol unless the environment variable MPI_EAGERONLY is set to 1. Default value is 16384 bytes.

MPI_SHM_RENDVSIZE

Messages communicated by shared memory that are greater than this size will use the rendezvous protocol unless the environment variable MPI_EAGERONLY is set. The default value is 24576 bytes.

MPI_TCP_RENDVSIZE

Messages communicated by TCP that contain data of this size and greater will use the rendezvous protocol unless the environment variable MPI_EAGERONLY is set. Default value is 49152 bytes.