QLogic OFED+ Host Software User Guide, Rev. B

4–Running QLogic MPI on QLogic Adapters
QLogic MPI Details
Using mpirun
• As noted in “Compile and Run an Example C Program” on page 4-4, you
can use the command line option -m:
$mpirun -np n -m mpihosts [other options] program-name
In this case, if the named file cannot be opened, the MPI job fails.
An alternate mechanism to -m for specifying hosts is the -H or -hosts
followed by a host list. The host list can follow one of the following examples:
host-[01-02,04,06-08] , or
host-01,host-02,host-04,host-06,host-07,host-08
• When neither the -m or the -H options are used, mpirun checks the
environment variable MPIHOSTS for the name of the MPI hosts file. If this
variable is defined and the file it names cannot be opened, the MPI job fails.
• In the absence of the -m option, the -H option, and the MPIHOSTS
environment variable, mpirun uses the file ./mpihosts, if it exists.
• If none of these four methods of specifying the hosts file are used, mpirun
looks for the file ~/.mpihosts.
If you are working in the context of a batch queuing system, it may provide a job
submission script that generates an appropriate mpihosts file.
The script mpirun is a front end program that starts a parallel MPI job on a set of
nodes in an TrueScale cluster. mpirun may be run on any i386 or x86_64
machine inside or outside the cluster, as long as it is on a supported Linux
distribution, and has TCP connectivity to all TrueScale cluster machines to be
used in a job.
The script starts, monitors, and terminates the node programs. mpirun uses ssh
(secure shell) to log in to individual cluster machines and prints any messages
that the node program prints on stdout or stderr, on the terminal where
mpirun is invoked.
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