Developer Guide

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Setting the Number of Threads Using an OpenMP* Environment Variable

You can set the number of threads using the environment variable
OMP_NUM_THREADS
. To change the number of OpenMP threads, in the command shell in which the program is going to run,
enter:
set OMP_NUM_THREADS=
<number of threads to use>
.
Some shells require the variable and its value to be exported:
export OMP_NUM_THREADS=
<number of threads to use>
.
You can alternatively assign value to the environment variable using Microsoft Windows*
OS Control Panel.
Note that you will not benefit from setting this variable on Microsoft Windows* 98 or
Windows* ME because multiprocessing is not supported.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804