Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

mkl_set_dynamic

Enables
Intel® oneAPI Math Kernel Library
 to dynamically change the number of OpenMP* threads.

Syntax

void
mkl_set_dynamic
(
int
flag
);
Include Files
  • mkl.h
Input Parameters
Name
Type
Description
flag
int
flag
 = 0 - Requests disabling dynamic adjustment of the number of threads.
flag
≠
 0 - Requests enabling dynamic adjustment of the number of threads.
Description
This function indicates whether
Intel® oneAPI Math Kernel Library
 can dynamically change the number of OpenMP threads or should avoid doing this. The setting applies to all
Intel® oneAPI Math Kernel Library
 functions on all execution threads. This function takes precedence over the
MKL_DYNAMIC
 environment variable.
Dynamic adjustment of the number of threads is enabled by default. Specifically,
Intel® oneAPI Math Kernel Library
 may use fewer threads in parallel regions than the number returned by themkl_get_max_threadsfunction. Disabling dynamic adjustment of the number of threads does not ensure that
Intel® oneAPI Math Kernel Library
 actually uses the specified number of threads, although the library attempts to use that number.
If you call
Intel® oneAPI Math Kernel Library
 from within an OpenMP parallel region and want to create internal parallel regions, either disable dynamic adjustment of the number of threads or set the thread-local number of threads (seemkl_set_num_threads_local for how to do it).

Example

#include "mkl.h"
…
mkl_set_num_threads( 8 );
#pragma omp parallel
{
	my_compute_with_mkl();	// Intel MKL uses 1 thread, being called from OpenMP parallel region
	mkl_set_dynamic( 0 );	// disable adjustment of the number of threads
	my_compute_with_mkl();	// Intel MKL uses 8 threads
}

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.