Developer Reference for Intel® oneAPI Math Kernel Library for C

ID 766684
Date 3/31/2023
Public

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Document Table of 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.

NOTE:

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