Intel® MPI Library

Interoperability with OpenMP API

I_MPI_PIN_DOMAIN

Intel® MPI Library provides an additional environment variable to control process pinning for hybrid MPI/OpenMP* applications. This environment variable is used to define a number of non-overlapping subsets (domains) of logical processors on a node, and a set of rules on how MPI processes are bound to these domains by the following formula: one MPI process per one domain. See the picture below.

Timer Control

I_MPI_TIMER_KIND

Select the timer used by the MPI_Wtime and MPI_Wtick calls.

Syntax

I_MPI_TIMER_KIND=<timername>

Arguments

<timername>

Define the timer type

gettimeofday

Glossary

cell

A pinning resolution in descriptions for pinning property.

hyper-threading technology

A feature within the IA-64 and Intel® 64 family of processors, where each processor core provides the functionality of more than one logical processor.

logical processor

Binding Option

-binding

Use this option to pin or bind MPI processes to a particular processor and avoid undesired process migration. In the following syntax, the quotes may be omitted for a one-member list. Each parameter corresponds to a single pinning property.

Collective Operations Control

Each collective operation in the Intel® MPI Library supports a number of communication algorithms. In addition to highly optimized default settings, the library provides a way to control the algorithm selection explicitly. You can do this by using the I_MPI_ADJUST environment variable family, which is described in the following section.

MPMD Launch Mode

Intel® MPI Library supports the multiple programs, multiple data (MPMD) launch mode. There are two ways to do this.

The easiest way is to create a configuration file and pass it to the -configfile option. A configuration file should contain a set of arguments for mpirun, one group per line. For example:

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