Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

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

mkl_set_num_threads

Specifies the number of OpenMP* threads to use.

Syntax

void mkl_set_num_threads
(
int
nt
)
;
Include Files
  • mkl.h
Input Parameters
Name
Type
Description
nt
int
nt
 > 0 - The number of threads suggested by the user.
nt
≤
 0 - Invalid value, which is ignored.
Description
This function enables you to specify how many OpenMP threads
Intel® oneAPI Math Kernel Library
 should use for internal parallel regions. If this number is not set (default),
Intel® oneAPI Math Kernel Library
 functions use the default number of threads for the OpenMP run-time library. The specified number of threads applies:
  • To all
    Intel® oneAPI Math Kernel Library
     functions except the functions from the domains where the number of threads is set withmkl_domain_set_num_threads
  • To all execution threads except the threads where the number of threads is set with mkl_set_num_threads_local
The number specified is a hint, and
Intel® oneAPI Math Kernel Library
 may actually use a smaller number.
This function takes precedence over the
MKL_NUM_THREADS
 environment variable.

Example

#include "mkl.h"
…
mkl_set_num_threads(4);
my_compute_using_mkl();	// Intel MKL uses up to 4 OpenMP threads

Product and Performance Information

1

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