Math Kernel Library Developer Guide
Intel® oneAPI Math Kernel Library threading layer defines how Intel® oneAPI Math Kernel Library functions utilize multiple computing cores of the system that the application runs on. You must link your application with one appropriate Intel® oneAPI Math Kernel Library library in this layer, as explained below. Depending on whether this is a threading or a sequential library, Intel® oneAPI Math Kernel Library runs in a parallel or sequential mode, respectively.
In the parallel mode, Intel® oneAPI Math Kernel Library utilizes multiple processor cores available on your system, uses the OpenMP*or Intel TBB threading technology, and requires a proper threading run-time library (RTL) to be linked with your application. Independently of use of Intel® oneAPI Math Kernel Library, the application may also require a threading RTL. You should link not more than onethreading RTL to your application. Threading RTLs are provided by your compiler. Intel® oneAPI Math Kernel Library provides several threading libraries, each dependent on thethreading RTL of a certain compiler, and your choice of the Intel® oneAPI Math Kernel Library threading library must be consistent with thethreading RTL that you use in your application.
The OpenMP RTL of the Intel® compiler is the libiomp5.so library, located under <parent directory>/compiler/lib. This RTL is compatible with the GNU* compilers (gcc and gfortran). You can find additional information about the Intel OpenMP RTL at https://www.openmprtl.org.
The Intel TBB RTL of the Intel® compiler is the libtbb.so library, located under <parent directory>/tbb/lib. You can find additional information about the Intel TBB RTL at https://www.threadingbuildingblocks.org.
In the sequential mode, Intel® oneAPI Math Kernel Library runs unthreaded code, does not require anthreading RTL, and does not respond to environment variables and functions controlling the number of threads. Avoid using the library in the sequential mode unless you have a particular reason for that, such as the following:
It is critical to link the application with the proper RTL. The table below explains what library in the Intel® oneAPI Math Kernel Library threading layer and whatthreading RTL you should choose under different scenarios:
Application |
Intel® oneAPI Math Kernel Library |
RTL Required |
||
---|---|---|---|---|
Uses OpenMP | Compiled with | Execution Mode |
Threading Layer |
|
no |
any compiler |
parallel |
Static linking: libmkl_intel_thread.a Dynamic linking: libmkl_intel_thread.so |
libiomp5.so |
no |
any compiler |
parallel |
Static linking: libmkl_tbb_thread.a Dynamic linking: libmkl_tbb_thread.so |
libtbb.so |
no |
any compiler |
sequential |
Static linking: libmkl_sequential.a Dynamic linking: libmkl_sequential.so |
none† |
yes |
Intel compiler |
parallel |
Static linking: libmkl_intel_thread.a Dynamic linking: libmkl_intel_thread.so |
libiomp5.so |
yes |
GNU compiler |
parallel |
Recommended! | |
Static linking: libmkl_intel_thread.a Dynamic linking: libmkl_intel_thread.so |
libiomp5.so |
|||
yes |
GNU compiler |
parallel |
Static linking: libmkl_gnu_thread.a Dynamic linking: libmkl_gnu_thread.so |
GNU OpenMP RTL |
yes |
PGI* compiler |
parallel |
Static linking: libmkl_pgi_thread.a Dynamic linking: libmkl_pgi_thread.so |
PGI OpenMP RTL |
yes |
any other compiler |
parallel |
Not supported. Use Intel® oneAPI Math Kernel Library in the sequential mode. |
† For the sequential mode, add the POSIX threads library (libpthread) to your link line because the libmkl_sequential.a and libmkl_sequential.so libraries depend on libpthread.
Optimization Notice |
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Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice. Notice revision #20110804 |