QLogic OFED+ Host Software User Guide, Rev. B

4–Running QLogic MPI on QLogic Adapters
QLogic MPI Details
NOTE:
When the -np value is larger than the number of nodes in the mpihosts file
times the -ppn value, mpirun cycles back through the hostsfile, assigning
additional node programs per host.
Typically, the number of node programs should not be larger than the number of
processor cores, at least not for compute-bound programs.
This option specifies the number of processes to spawn. If this option is not set,
then environment variable MPI_NPROCS is checked. If MPI_NPROCS is not set,
the default is to determine the number of processes based on the number of hosts
in the machinefile -M or the list of hosts -H.
-ppn processes-per-node
This option creates up to the specified number of processes per node.
Each node program is started as a process on one node. While a node program
may fork child processes, the children themselves must not call MPI functions.
The -distributed=on|off option has been added to mpirun. This option
reduces overhead by enabling mpirun to start processes in parallel on multiple
nodes. Initially, mpirun spawns one mpirun child per node from the root node,
each of which in turn spawns the number of local processes for that particular
node. Control the use of distributed mpirun job spawning mechanism with this
option:
-distributed [=on|off]
The default is on. To change the default, put this option in the global
mpirun.defaults file or a user-local file. See “Environment for Node
Programs” on page 4-19 and “Environment Variables” on page 4-20 for details.
mpirun monitors the parallel MPI job, terminating when all the node programs in
that job exit normally, or if any of them terminates abnormally.
Killing the mpirun program kills all the processes in the job. Use CTRL+C to kill
mpirun.
Console I/O in MPI Programs
mpirun sends any output printed to stdout or stderr by any node program to
the terminal. This output is line-buffered, so the lines output from the various node
programs will be non-deterministically interleaved on the terminal. Using the -l
option to mpirun will label each line with the rank of the node program where it
was produced.
Node programs do not normally use interactive input on stdin, and by default,
stdin is bound to /dev/null. However, for applications that require standard
input redirection, QLogic MPI supports two mechanisms to redirect stdin:
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