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Run-Time Library Routines

Overview:

Routine Purpose
OMP_SET_NUM_THREADS Sets the number of threads that will be used in the next parallel region
OMP_GET_NUM_THREADS Returns the number of threads that are currently in the team executing the parallel region from which it is called
OMP_GET_MAX_THREADS Returns the maximum value that can be returned by a call to the OMP_GET_NUM_THREADS function
OMP_GET_THREAD_NUM Returns the thread number of the thread, within the team, making this call.
OMP_GET_THREAD_LIMIT Returns the maximum number of OpenMP threads available to a program
OMP_GET_NUM_PROCS Returns the number of processors that are available to the program
OMP_IN_PARALLEL Used to determine if the section of code which is executing is parallel or not
OMP_SET_DYNAMIC Enables or disables dynamic adjustment (by the run time system) of the number of threads available for execution of parallel regions
OMP_GET_DYNAMIC Used to determine if dynamic thread adjustment is enabled or not
OMP_SET_NESTED Used to enable or disable nested parallelism
OMP_GET_NESTED Used to determine if nested parallelism is enabled or not
OMP_SET_SCHEDULE Sets the loop scheduling policy when "runtime" is used as the schedule kind in the OpenMP directive
OMP_GET_SCHEDULE Returns the loop scheduling policy when "runtime" is used as the schedule kind in the OpenMP directive
OMP_SET_MAX_ACTIVE_LEVELS Sets the maximum number of nested parallel regions
OMP_GET_MAX_ACTIVE_LEVELS Returns the maximum number of nested parallel regions
OMP_GET_LEVEL Returns the current level of nested parallel regions
OMP_GET_ANCESTOR_THREAD_NUM Returns, for a given nested level of the current thread, the thread number of ancestor thread
OMP_GET_TEAM_SIZE Returns, for a given nested level of the current thread, the size of the thread team
OMP_GET_ACTIVE_LEVEL Returns the number of nested, active parallel regions enclosing the task that contains the call
OMP_IN_FINAL Returns true if the routine is executed in the final task region; otherwise it returns false
OMP_INIT_LOCK Initializes a lock associated with the lock variable
OMP_DESTROY_LOCK Disassociates the given lock variable from any locks
OMP_SET_LOCK Acquires ownership of a lock
OMP_UNSET_LOCK Releases a lock
OMP_TEST_LOCK Attempts to set a lock, but does not block if the lock is unavailable
OMP_INIT_NEST_LOCK Initializes a nested lock associated with the lock variable
OMP_DESTROY_NEST_LOCK Disassociates the given nested lock variable from any locks
OMP_SET_NEST_LOCK Acquires ownership of a nested lock
OMP_UNSET_NEST_LOCK Releases a nested lock
OMP_TEST_NEST_LOCK Attempts to set a nested lock, but does not block if the lock is unavailable
OMP_GET_WTIME Provides a portable wall clock timing routine
OMP_GET_WTICK Returns a double-precision floating point value equal to the number of seconds between successive clock ticks



For C/C++, all of the run-time library routines are actual subroutines. For Fortran, some are actually functions, and some are subroutines. For example:

Fortran

INTEGER FUNCTION OMP_GET_NUM_THREADS()

C/C++

#include <omp.h>
int omp_get_num_threads(void)