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3.12.1 omp_display_env – print the initial ICV values ¶

Description:

Each time this routine is invoked, the OpenMP version number and initial value of internal control variables (ICVs) is printed on stderr. The displayed values are those at startup after evaluating the environment variables; later calls to API routines or clauses used in enclosing constructs do not affect the output.

If the verbose argument is false, only the OpenMP version and standard OpenMP ICVs are shown; if it is true, additionally, the GCC-specific ICVs are shown.

The output consists of multiple lines and starts with ‘OPENMP DISPLAY ENVIRONMENT BEGIN’ followed by the name-value lines and ends with ‘OPENMP DISPLAY ENVIRONMENT END’. The name is followed by an equal sign and the value is enclosed in single quotes.

The first line has as name either ‘_OPENMP’ or ‘openmp_version’ and shows as value the supported OpenMP version number (4-digit year, 2-digit month) of the implementation, matching the value of the _OPENMP macro and, in Fortran, the named constant openmp_version.

In each of the succeeding lines, the name matches the environment-variable name of an ICV and shows its value. Those line are might be prefixed by pair of brackets and a space, where the brackets enclose a comma-separated list of devices to which the ICV-value combination applies to; the value can either be a numeric device number or an abstract name denoting all devices (all), the initial host device (host) or all devices but the host (device). Note that the same ICV might be printed multiple times for multiple devices, even if all have the same value.

The effect when invoked from within a target region is unspecified.

C/C++:

Prototype:

void omp_display_env(int verbose)

Fortran:

Interface:	subroutine omp_display_env(verbose)
	logical, intent(in) :: verbose

Example:

Note that the GCC-specific ICVs, such as the shown GOMP_SPINCOUNT, are only printed when verbose set to true.

OPENMP DISPLAY ENVIRONMENT BEGIN
  _OPENMP = '201511'
  [host] OMP_DYNAMIC = 'FALSE'
  [host] OMP_NESTED = 'FALSE'
  [all] OMP_CANCELLATION = 'FALSE'
  ...
  [host] GOMP_SPINCOUNT = '300000'
OPENMP DISPLAY ENVIRONMENT END

See also:

OMP_DISPLAY_ENV – Show OpenMP version and environment variables, OpenMP Environment Variables, Implementation-defined ICV Initialization

Reference:

OpenMP specification v5.1, Section 3.15