I_MPI_FABRICS

This topic is an excerpt from the Intel® MPI Library Reference Manual for Linux* OS which provides further details on the I_MPI_FABRICS environment variable.

Select a particular network fabric to be used for communication.

Syntax

I_MPI_FABRICS=<fabric>|<intra-node fabric>:<inter-nodes fabric>

Where

<fabric> := {shm, dapl, tcp, tmi, ofa, ofi}
<intra-node fabric> := {shm, dapl, tcp, tmi, ofa, ofi}
<inter-nodes fabric> := {dapl, tcp, tmi, ofa, ofi}

Arguments

Argument	Definition
`<fabric>`	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*)
`ofi`	OFI (OpenFabrics Interfaces)-capable network fabric including Intel® True Scale Fabric, and TCP (through OFI API)

For example, to select the winOFED* 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 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.