User guide

4–Running MPI on QLogic Adapters
Open MPI
IB0054606-02 A 4-13
 The command line option -hostfile can be used as shown in the
following command line:
$mpirun -np n -hostfile mpihosts [other options]
program-name
or -machinefile is a synonym for -hostfile. In this case, if the named
file cannot be opened, the MPI job fails.
An alternate mechanism to -
hostfile for specifying hosts is the -H,
-hosts, or --host followed by a host list. The host list can follow one of
the following examples:
host-01, or
host-01,host-02,host-04,host-06,host-07,host-08
 In the absence of the -hostfile option, the -H option, mpirun uses the
file ./mpihosts, if it exists.
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. More details
about how to schedule processes to nodes with Open MPI refer to the Open MPI
website:
http://www.open-mpi.org/faq/?category=running#mpirun-scheduling
Using Open MPI’s mpirun
The script mpirun is a front end program that starts a parallel MPI job on a set of
nodes in an IB cluster. mpirun may be run on any x86_64 machine inside or
outside the cluster, as long as it is on a supported Linux distribution, and has TCP
connectivity to all IB 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.
The general syntax is:
$ mpirun [mpirun_options...] program-name [program options]
program-name is usually the pathname to the executable MPI program. When
the MPI program resides in the current directory and the current directory is not in
your search path, then program-name
must begin with ‘./’, for example:
./program-name
Unless you want to run only one instance of the program, use the -np option, for
example:
$ mpirun -np n [other options] program-name