MPI_SHM_SHORTMSGSIZE

The size (in bytes) of the section of a postbox that contains either data or a buffer list. The default value is 256 bytes.

If MPI_SHM_PIPESTART, MPI_SHM_PIPESIZE, or MPI_SHM_CYCLESIZE is increased to a size larger than 31744 bytes, then MPI_SHM_SHORTMSGSIZE may also have to be increased. See Chapter 3, Performance Tuning for more information.