mkl_set_dynamic

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/31/2023

Version

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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.

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 theMKL_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.

TIP:

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
}

Parent topic: Threading Control

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Developer Reference for Intel® oneAPI Math Kernel Library for C

mkl_set_dynamic