MPICH-GM is a variant
of the MPICH implementation
of MPI which has been adapted
for use with the GM
communication layer running over Myrinet.
MPICH-GM provides high-bandwidth, low-latency message passing services
which are particularly useful for communication-intensive or latency-sensitive
parallel application programs. Unlike MPICH, MPICH-GM is available on
SciClone in both 32-bit (v8plusa, v8plusb) and 64-bit (v9a, v9b) versions.
The MPE
profiling and debugging extensions are not available with MPICH-GM.
MPICH-GM programs on
SciClone must be initiated via PBS using
the pbsmpichgm
command rather than with mpirun or mpd. See the SciClone
User's Guide and pbsmpichgm
man page for complete details.
Programs compiled with
MPICH-GM can be run without modification on either of SciClone's Myrinet
networks (Myrinet-1280 on the tornado and gulfstream subclusters
or Myrinet-2000 on the hurricane and twister subclusters).
Note that these two networks are disjoint, so it is not possible to
run a single MPICH-GM application which spans both of them.
Environment Variables
For proper operation,
the MPICH environment variable must be set in the user's ~/.cshrc file
to select which MPICH package to use (MPICH or MPICH-GM) and the desired
variant ([v8plusa,v9a]/generic or [v8plusb,v9b]/ultra3cu).
$MPICH/bin should be in the user's search path, and $MPICH/man should
be included in the MANPATH. The file /usr/local/etc/templates/cshrc
contains the current recommended environment settings and includes options
for specifying which version of MPICH-GM to use, and for switching between
MPICH-GM and other MPI packages.
