Math Kernel Library Developer Guide

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 orWindows* ME because multiprocessing is not supported.

See Also