QLogic OFED+ Host Software User Guide, Rev. B

4–Running QLogic MPI on QLogic Adapters
QLogic MPI Details
NOTE:
The mpi-frontend-* RPM needs to be installed on all nodes that will be
using mpirun. Alternatively, you can use the mpirun option
-distributed=off, which requires that only the mpi-frontend RPM is
installed on the node where mpirun is invoked. Using -distributed=off
can have a negative impact on mpirun’s performance when running
large-scale jobs. More specifically, this option increases the memory usage
on the host where mpirun is started and will slow down the job startup,
since it will spawn MPI processes serially.
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
This option spawns n instances of program-name. These instances are called
node programs.
Generally, mpirun tries to distribute the specified number of processes evenly
among the nodes listed in the mpihosts file. However, if the number of
processes exceeds the number of nodes listed in the mpihosts file, then some
nodes will be assigned more than one instance of the program.
Another command line option, -ppn, instructs mpirun to assign a fixed number p
of node programs (processes) to each node, as it distributes n instances among
the nodes:
$ mpirun -np n -m mpihosts -ppn p program-name
This option overrides the :process_count specifications, if any, in the lines of
the mpihosts file. As a general rule, mpirun distributes the n node programs
among the nodes without exceeding, on any node, the maximum number of
instances specified by the :process_count option. The value of
the :process_count option is specified by either the -ppn command line
option or in the mpihosts file.
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