The

MKL_DYNAMIC

environment variable enables

Intel® oneAPI Math Kernel Library

to dynamically change the number of threads.

The default value of

MKL_DYNAMIC

is

TRUE

, regardless of

OMP_DYNAMIC

, whose default value may be

FALSE

.

When

MKL_DYNAMIC

is

TRUE,

Intel® oneAPI Math Kernel Library

may use fewer OpenMP threads than the maximum number you specify.

For example,

MKL_DYNAMIC

set to

TRUE

enables optimal choice of the number of threads in the following cases:

When

MKL_DYNAMIC

is

FALSE

,

Intel® oneAPI Math Kernel Library

uses the suggested number of OpenMP threads whenever the underlying algorithms permit.For example, if you attempt to do a size one matrix-matrix multiply across eight threads, the library may instead choose to use only one thread because it is impractical to use eight threads in this event.

If

Intel® oneAPI Math Kernel Library

is called from an OpenMP parallel region in your program,

Intel® oneAPI Math Kernel Library

uses only one thread by default. If you want

Intel® oneAPI Math Kernel Library

to go parallel in such a call, link your program against an OpenMP threading RTL supported by

Intel® oneAPI Math Kernel Library

and set the environment variables:

With these settings,

Intel® oneAPI Math Kernel Library

uses

MKL_NUM_THREADS

threads when it is called from the OpenMP parallel region in your program.

In general, set

MKL_DYNAMIC

to

FALSE

only under circumstances that

Intel® oneAPI Math Kernel Library

is unable to detect, for example, to use nested parallelism where the library is already called from a parallel section.