omp_set_num_threads
void omp_set_num_threads (int numThreads);
Purpose
Specifies the number of threads used for subsequent parallel regions.
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Note The OpenMP Run-Time Library is available only in the LabWindows/CVI Full Development System. |
LabWindows/CVI determines the number of threads used for a parallel region by the following rules (in order of precedence):
- The value specified by the num_threads clause, else
- The value specified by the omp_set_num_threads function, else
- The value of the OMP_NUM_THREADS environment variable, else
- The number of logical processors
For more information on the rules governing the number of threads used to execute a parallel region, refer to Section 2.4.1 of the OpenMP 2.5 specification.
When called from the sequential part of the program, this function overrides the implementation-defined default value for the number of threads and the value of the OMP_NUM_THREADS environment variable.
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Note Each call to this function overwrites the previous value. Therefore, when you call this function from within a parallel region, LabWindows/CVI determines the final value by the last thread that executes this function. Since execution order within a thread is non-deterministic, you should not call this function from within a parallel region. |
To determine number of threads used for subsequent parallel regions, use the omp_get_max_threads function.
Binding thread set: all threads
Parameters
| Input | ||
| Name | Type | Description |
| numThreads | int | The number of threads used for subsequent parallel regions. The value must be between 1 and 64. LabWindows/CVI ignores all other values. |
Return Value
None.
Additional Information
Library: OpenMP Run-Time Library
Include file: omp.h
LabWindows/CVI compatibility: LabWindows/CVI 2013 and later