Originally posted by: RoyHu

The IBM XL C/C++ compiler, V12.1 starts to support a new environment variable OMP_PROC_BIND. You can use it to control whether OpenMP threads are allowed to move between processors.

Syntax:
>>-OMP_PROC_BIND=--+-TRUE--+-----------------------------------><
                                                  '-FALSE-' 

Parameters:

TRUE:    Bounds the threads to processors.

FALSE: Supports threads to be moved between processors.

Rules:

If OMP_PROC_BIND is set to true and the suboptions of XLSMPOPTS (i.e. startproc/stride, procs, bind or bindlist) are also set, the threads are bound according to the settings in XLSMPOPTS environment  variable.

If OMP_PROC_BIND is set to false, the startproc/stride, procs, bind and bindlist suboptions of XLSMPOPTS environment variable are ignored.

Reference:

• For more information about the usage of the OMP_NUM_THREADS environment variable, visit the topic at http://pic.dhe.ibm.com/infocenter/comphelp/v121v141/topic/com.ibm.xlc121.aix.doc/compiler_ref/omp_proc_bind.html
• For more information about the usage of XLSMPOPTS environment variable, visit the topic at http://pic.dhe.ibm.com/infocenter/comphelp/v121v141/topic/com.ibm.xlc121.aix.doc/compiler_ref/env_var_xlsmpopts.html