HP-MPI User's Guide (11th Edition)

Tuning
Tunable parameters
Chapter 5184
-intra
The -intra command line option controls how messages are transferred
to local processes and can impact performance when multiple ranks
execute on a host. See “Local host communication method” on page 121
for more information.
MPI_RDMA_INTRALEN, MPI_RDMA_MSGSIZE,
MPI_RDMA_NENVELOPE
These environment variables control various aspects of the way message
traffic is handled on RDMA networks. The default settings have been
carefully selected to be appropriate for the majority of applications.
However, some applications may benefit from adjusting these values
depending on their communication patterns. See the corresponding man
pages for more information.
MPI_USE_LIBELAN_SUB
Setting this environment variable may provide some performance
benefits on the ELAN interconnect. However, some applications may
experience resource problems. See “MPI_USE_LIBELAN_SUB” on
page 161 for more information.