SPEC MPI2007 Flag Description for the Intel(R) C++ Compiler 12.1 for IA32 and Intel 64 applications and Intel(R) Fortran Compiler 12.1 for IA32 and Intel 64 applications

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Optimization Flags

Portability Flags

Compiler Flags

System and Other Tuning Information

Intel(R) MPI Library 4.0.3 for Linux* options and environment variables

Job startup command flags

-n <# of processes> or -np <# of processes>

Use this option to set the number of MPI processes to run the current arg-set.

-perhost <# of processes>

Use this option to place the indicated number of consecutive MPI processes on every host in group round robin fashion. The number of processes to start is controlled by the option -n as usual.


Use this option to allow parallel fast starting of mpd daemons under one local root. No daemon checking is performed.

-genv <ENVVAR> <value>

Use this option to set the <ENVVAR> environment variable to the specified <value> for all MPI processes.

Environment variables


Select the particular network fabric to be used.

sock - Sockets

shm - Shared-memory only (no sockets)

ssm - Combined sockets + shared memory (for clusters with SMP nodes)

rdma - RDMA-capable network fabrics including InfiniBand*, Myrinet* (via DAPL*)

rdssm - Combined sockets + shared memory + DAPL* (for clusters with SMP nodes and RDMA-capable network fabrics)


Set this environment variable to enable fallback to the available fabric. It is valid only for rdssm and rdma modes.

Fall back to the shared memory and/or socket fabrics if initialization of the DAPL* fabric fails. This is the default value.

Terminate the job if the fabric selected by the I_MPI_DEVICE environment variable cannot be initialized.