User`s guide

Intel® MPI Library User’s Guide for Linux* OS

Arguments

Argument

Definition

Define a network fabric

shm

Shared-memory

dapl

DAPL-capable network fabrics, such as InfiniBand*, iWarp*,

Dolphin*, and XPMEM* (through DAPL*)

tcp

TCP/IP-capable network fabrics, such as Ethernet and

InfiniBand* (through IPoIB*)

tmi

Network fabrics with tag matching capabilities through the Tag

Matching Interface (TMI), such as Intel® True Scale Fabric and

Myrinet*

ofa

Network fabric, such as InfiniBand* (through OpenFabrics*

Enterprise Distribution (OFED*) verbs) provided by the Open

Fabrics Alliance* (OFA*)

For example, to select the OFED* InfiniBand* device, use the following command:

$ mpirun -n <# of processes> \

-env I_MPI_FABRICS shm:dapl <executable>

For these devices, if <provider> is not specified, the first DAPL* provider in the /etc/dat.conf

file is used. The shm fabric is available for both Intel® and non-Intel microprocessors, but it may

perform additional optimizations for Intel microprocessors than it performs for non-Intel

microprocessors.

NOTE

Ensure the selected fabric is available. For example, use shm only if all the processes can

communicate with each other through the availability of the /dev/shm device. Use dapl only

when all processes can communicate with each other through a single DAPL provider.

2.7. Running an MPI Program

To launch programs linked with the Intel® MPI Library, use the mpirun command, as follows:

$ mpirun -n <# of processes> ./myprog

This command invokes the mpiexec.hydra command. Use the mpiexec.hydra options on the

mpirun command line.

Use the -n option to set the number of MPI processes. If the -n option is not specified, the

program is either be pulled from a job scheduler, or uses the number of cores on the machine if

this program is not under a scheduler.