HP aC++/HP C A.06.20 Programmer's Guide

omp_in_parallel
#include <omp.h>
int omp_in_parallel(void);
The omp_in_parallel function returns non-zero if it is called within the dynamic
extent of a parallel region executing in parallel; otherwise, it returns 0. This function
returns non-zero from within a region executing in parallel, including nested regions
that are serialized.
omp_set_dynamic
#include <omp.h>
void omp_set_dynamic(int dynamic_threads);
The omp_set_dynamic function enables or disables dynamic adjustment of the number
of threads available for execution of parallel regions. This function has effect only when
called from serial portions of the program. If it is called from a portion of the program
where the omp_in_parallel function returns non-zero, the behavior of the function
is undefined. If dynamic_threads evaluates to non-zero, the number of threads that
are used for executing subsequent parallel regions may be adjusted automatically by
the runtime environment to best utilize system resources. As a consequence, the number
of threads specified by the user is the maximum thread count. The number of threads
always remains fixed over the duration of each parallel region and is reported by the
omp_get_num_threads function. If dynamic_threads evaluates to 0, dynamic
adjustment is disabled. A call to omp_set_dynamic has precedence over the
OMP_DYNAMIC environment variable.
The default for the dynamic adjustment of threads is 0.
omp_get_dynamic
#include <omp.h>
int omp_get_dynamic(void);
The omp_get_dynamic function returns non-zero if dynamic thread adjustment is
enabled and returns 0 otherwise.
omp_set_nested
#include <omp.h>
void omp_set_nested(int nested);
The omp_set_nested function enables or disables nested parallelism. If nested
evaluates to 0, which is the default, nested parallelism is disabled, and nested parallel
regions are serialized and executed by the current thread. If nested evaluates to non-zero,
nested parallelism is enabled, and parallel regions that are nested may deploy additional
threads to form the team. This call has precedence over the OMP_NESTED environment
variable.
Parallel Programming Using OpenMP 223