OMP_DISPLAY_ENV

When a program that uses the OpenMP runtime is invoked and the OMP_DISPLAY_ENV environment variable is set, the OpenMP runtime library displays the values of the internal control variables (ICVs) associated with the environment variables and the build-specific information about the runtime library.

OMP_DISPLAY_ENV is useful in the following cases:

When the runtime library is statically linked with an OpenMP program, you can use OMP_DISPLAY_ENV to check the version of the library that is used during link time.
When the runtime library is dynamically linked with an OpenMP program, you can use OMP_DISPLAY_ENV to check the library that is used at run time.
You can use OMP_DISPLAY_ENV to check the current setting of the runtime environment.

By default, no information is displayed.

The syntax of this environment variable is as follows:


>>-OMP_DISPLAY_ENV--=--+-TRUE----+-----------------------------><
                       +-FALSE---+   
                       '-VERBOSE-'

Note: The values TRUE, FALSE, and VERBOSE are not case-sensitive.

TRUE: Displays the OpenMP version number defined by the _OPENMP macro and the initial ICV values for the OpenMP environment variables.
FALSE: Instructs the runtime environment not to display any information.
VERBOSE: Displays build-specific information, ICV values associated with OpenMP environment variables, and the setting of the XLSMPOPTS environment variable.

Usage

When OMP_DISPLAY_ENV is TRUE, the initial ICV values for the OpenMP environment variables are displayed. If OMP_PLACES is set to cores or threads, the OMP_PLACES value is displayed in the format of cores or threads followed by the number of places in brackets; for example, OMP_PLACES='cores(4)'. For custom OMP_PLACES, each resource is displayed individually in each place, followed by the keyword custom; for example, OMP_PLACES='{4,5,6,7},{8,9,10,11}' custom.

When OMP_DISPLAY_ENV is VERBOSE, the output includes a section that is delineated by the lines OPENMP DISPLAY AFFINITY BEGIN and OPENMP DISPLAY AFFINITY END. This section includes a verbose display of the OMP_PLACES value, where each resource for each place is displayed individually, followed by cores, threads, or custom as appropriate. This section also displays information on THREADS_PER_PLACE in the format of a comma-separated list of the individual THREADS_PER_PLACE value for each place; for example, THREADS_PER_PLACE='{2},{2}'.

Examples

Example 1

If you enter the export OMP_DISPLAY_ENV=TRUE command, you will get output that is similar to the following example:

OPENMP DISPLAY ENVIRONMENT BEGIN
  OMP_DISPLAY_ENV='TRUE'

  _OPENMP='201107'
  OMP_DYNAMIC='FALSE'
  OMP_MAX_ACTIVE_LEVELS='5'
  OMP_NESTED='FALSE'
  OMP_NUM_THREADS='96'
  OMP_PROC_BIND='FALSE'
  OMP_SCHEDULE='STATIC,0'
  OMP_STACKSIZE='4194304'
  OMP_THREAD_LIMIT='96'
  OMP_WAIT_POLICY='PASSIVE'
OPENMP DISPLAY ENVIRONMENT END

Example 2

If you enter the export OMP_DISPLAY_ENV=VERBOSE command, you will get output that is similar to the following example:

OPENMP DISPLAY AFFINITY BEGIN
 OMP_PLACES='{0},{1},{2},{3},{4},{5},{6},{7},{8},{9},{10}' cores
 THREADS_PER_PLACE='{1},{1},{1},{1},{1},{1},{1},{1},{1},{1},{1}'
OPENMP DISPLAY AFFINITY END

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