Developer Guide

Developer Guide for Intel® oneAPI Math Kernel Library Linux*

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ID 766690
Date 12/16/2022
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Document Table of Contents
Document Table of Contents x
Developer Guide for Intel® oneAPI Math Kernel Library for Linux*
Developer Guide for Intel® oneAPI Math Kernel Library for Linux* x
Getting Help and Support What's New Notational Conventions Related Information Getting Started Structure of the Intel® oneAPI Math Kernel Library Linking Your Application with the Intel® oneAPI Math Kernel Library Managing Performance and Memory Language-specific Usage Options Obtaining Numerically Reproducible Results Coding Tips Managing Output Working with the Intel® oneAPI Math Kernel Library Cluster Software Managing Behavior of the Intel® oneAPI Math Kernel Library with Environment Variables Configuring Your Integrated Development Environment to Link with Intel® oneAPI Math Kernel Library Intel® oneAPI Math Kernel Library Benchmarks Appendix A: Intel® oneAPI Math Kernel Library Language Interfaces Support Appendix B: Support for Third-Party Interfaces Appendix C: Directory Structure in Detail Notices and Disclaimers
Getting Started x
Shared Library Versioning CMake Config for oneMKL Checking Your Installation Setting Environment Variables Compiler Support Using Code Examples What You Need to Know Before You Begin Using the Intel® oneAPI Math Kernel Library
Setting Environment Variables x
Scripts to Set Environment Variables Modulefiles to Set Environment Variables Automating the Process of Setting Environment Variables Using the CMake Config File
Structure of the Intel® oneAPI Math Kernel Library x
Architecture Support High-level Directory Structure Layered Model Concept
Linking Your Application with the Intel® oneAPI Math Kernel Library x
Linking Quick Start Linking Examples Linking in Detail Building Custom Shared Objects
Linking Quick Start x
Using the -qmkl Compiler Option Using the Single Dynamic Library Selecting Libraries to Link with Using the Link-line Advisor Using the Command-Line Link Tool
Linking Examples x
Linking on IA-32 Architecture Systems Linking on Intel(R) 64 Architecture Systems
Linking in Detail x
Listing Libraries on a Link Line Dynamically Selecting the Interface and Threading Layer Linking with Interface Libraries Linking with Threading Libraries Linking with Computational Libraries Linking with Compiler Run-time Libraries Linking with System Libraries
Linking with Interface Libraries x
Using the ILP64 Interface vs. LP64 Interface Linking with Fortran 95 Interface Libraries
Building Custom Shared Objects x
Using the Custom Shared Object Builder Composing a List of Functions Specifying Function Names Distributing Your Custom Shared Object
Managing Performance and Memory x
Improving Performance with Threading Improving Performance for Small Size Problems Other Tips and Techniques to Improve Performance Using Memory Functions
Improving Performance with Threading x
OpenMP* Threaded Functions and Problems Functions Threaded with Intel® Threading Building Blocks Avoiding Conflicts in the Execution Environment Techniques to Set the Number of Threads Setting the Number of Threads Using an OpenMP* Environment Variable Changing the Number of OpenMP* Threads at Run Time Using Additional Threading Control Calling oneMKL Functions from Multi-threaded Applications Using Intel® Hyper-Threading Technology Managing Multi-core Performance Managing Performance with Heterogeneous Cores
Using Additional Threading Control x
oneMKL-specific Environment Variables for OpenMP Threading Control MKL_DYNAMIC MKL_DOMAIN_NUM_THREADS <span class='keyword'>MKL_NUM_STRIPES</span> Setting the Environment Variables for Threading Control
Improving Performance for Small Size Problems x
Using MKL_DIRECT_CALL in C Applications Using MKL_DIRECT_CALL in Fortran Applications Limitations of the Direct Call
Other Tips and Techniques to Improve Performance x
Coding Techniques Improving oneMKL Performance on Specific Processors Operating on Denormals
Using Memory Functions x
Avoiding Memory Leaks in oneMKL Using High-bandwidth Memory with oneMKL Redefining Memory Functions
Language-specific Usage Options x
Using Language-Specific Interfaces with Intel® oneAPI Math Kernel Library Mixed-language Programming with the Intel Math Kernel Library
Using Language-Specific Interfaces with Intel® oneAPI Math Kernel Library x
Interface Libraries and Modules Fortran 95 Interfaces to LAPACK and BLAS Compiler-dependent Functions and Fortran 90 Modules
Mixed-language Programming with the Intel Math Kernel Library x
Calling LAPACK, BLAS, and CBLAS Routines from C/C++ Language Environments Using Complex Types in C/C++ Calling BLAS Functions that Return the Complex Values in C/C++ Code
Obtaining Numerically Reproducible Results x
Getting Started with Conditional Numerical Reproducibility Specifying Code Branches Reproducibility Conditions Setting the Environment Variable for Conditional Numerical Reproducibility Code Examples
Coding Tips x
Example of Data Alignment Using Predefined Preprocessor Symbols for Intel® MKL Version-Dependent Compilation
Managing Output x
Using oneMKL Verbose Mode
Using oneMKL Verbose Mode x
Version Information Line Call Description Line
Working with the Intel® oneAPI Math Kernel Library Cluster Software x
Linking with oneMKL Cluster Software Setting the Number of OpenMP* Threads Using Shared Libraries Setting Environment Variables on a Cluster Interaction with the Message-passing Interface Using a Custom Message-Passing Interface Examples of Linking for Clusters
Examples of Linking for Clusters x
Examples for Linking a C Application Examples for Linking a Fortran Application
Managing Behavior of the Intel® oneAPI Math Kernel Library with Environment Variables x
Managing Behavior of Function Domains with Environment Variables Instruction Set Specific Dispatching on Intel® Architectures
Managing Behavior of Function Domains with Environment Variables x
Setting the Default Mode of Vector Math with an Environment Variable Managing Performance of the Cluster Fourier Transform Functions Managing Invalid Input Checking in LAPACKE Functions
Configuring Your Integrated Development Environment to Link with Intel® oneAPI Math Kernel Library x
Configuring the Eclipse* IDE CDT to Link with oneMKL
Intel® oneAPI Math Kernel Library Benchmarks x
Intel Optimized LINPACK Benchmark for Linux* Intel® Distribution for LINPACK* Benchmark Intel® Optimized High Performance Conjugate Gradient Benchmark
Intel Optimized LINPACK Benchmark for Linux* x
Contents of the Intel® Optimized LINPACK Benchmark Running the Software Known Limitations of the Intel® Optimized LINPACK Benchmark
Intel® Distribution for LINPACK* Benchmark x
Overview of the Intel® Distribution for LINPACK* Benchmark Contents of the Intel® Distribution for LINPACK* Benchmark Building the Intel® Distribution for LINPACK* Benchmark for a Customized MPI Implementation Building the Netlib HPL from Source Code Configuring Parameters Ease-of-use Command-line Parameters Running the Intel® Distribution for LINPACK* Benchmark Heterogeneous Support in the Intel® Distribution for LINPACK* Benchmark Environment Variables Improving Performance of Your Cluster
Intel® Optimized High Performance Conjugate Gradient Benchmark x
Overview of the Intel Optimized HPCG Versions of the Intel Optimized HPCG Getting Started with Intel Optimized HPCG Choosing Best Configuration and Problem Sizes
Appendix A: Intel® oneAPI Math Kernel Library Language Interfaces Support x
Language Interfaces Support, by Function Domain Include Files
Appendix B: Support for Third-Party Interfaces x
FFTW Interface Support
Appendix C: Directory Structure in Detail x
Detailed Structure of the IA-32 Architecture Directories Detailed Structure of the Intel® 64 Architecture Directories
Detailed Structure of the IA-32 Architecture Directories x
Static Libraries in the <span class='filepath'>lib</span> <span class='filepath'>/</span> <span class='filepath'>ia32</span> <span class='filepath'>_lin</span> Directory Dynamic Libraries in the <span class='filepath'>lib</span> <span class='filepath'>/</span> <span class='filepath'>ia32</span> <span class='filepath'>_lin</span> Directory
Detailed Structure of the Intel® 64 Architecture Directories x
Static Libraries in the <span class='filepath'>lib</span> <span class='filepath'>/</span> <span class='filepath'>intel64</span> <span class='filepath'>_lin</span> Directory Dynamic Libraries in the <span class='filepath'>lib</span> <span class='filepath'>/</span> <span class='filepath'>intel64</span> <span class='filepath'>_lin</span> Directory
Developer Guide for Intel® oneAPI Math Kernel Library for Linux*

Instruction Set Specific Dispatching on Intel® Architectures

Intel® oneAPI Math Kernel Library automatically queries and then dispatches the code path supported on your Intel® processor to the optimal instruction set architecture (ISA) by default. The MKL_ENABLE_INSTRUCTIONS environment variable or the mkl_enable_instructions support function enables you to dispatch to an ISA-specific code path of your choice. For example, you can run the Intel® Advanced Vector Extensions (Intel® AVX) code path on an Intel processor based on Intel® Advanced Vector Extensions 2 (Intel® AVX2), or you can run the Intel® Streaming SIMD Extensions 4.2 (Intel® SSE4.2) code path on an Intel AVX-enabled Intel processor. This feature is not available on non-Intel processors.

In some cases Intel® oneAPI Math Kernel Library also provides support for upcoming architectures ahead of hardware availability, but the library does not automatically dispatch the code path specific to an upcoming ISA by default. If for your exploratory work you need to enable an ISA for an Intel processor that is not yet released or if you are working in a simulated environment, you can use theMKL_ENABLE_INSTRUCTIONS environment variable or mkl_enable_instructions support function.

The following table lists possible values of MKL_ENABLE_INSTRUCTIONS alongside the corresponding ISA supported by a given processor. MKL_ENABLE_INSTRUCTIONSdispatches to the default ISA if the ISA requested is not supported on the particular Intel processor. For example, if you request to run the Intel AVX512 code path on a processor based on Intel AVX2, Intel® oneAPI Math Kernel Library runs the Intel AVX2 code path. The table also explains whether the ISA is dispatched by default on the processor that supports this ISA.

Value of
MKL_ENABLE_INSTRUCTIONS

ISA

Dispatched by Default

AVX512

Intel® Advanced Vector Extensions (Intel® AVX-512) for systems based on Intel® Xeon® processors

Yes

AVX512_E1

Intel® Advanced Vector Extensions (Intel® AVX-512) with support for Vector Neural Network Instructions.

Yes

AVX512_E2

ICX: Intel® Advanced Vector Extensions (Intel® AVX-512) enabled processors.

Yes

AVX512_E3

Intel® Advanced Vector Extensions 512 (Intel® AVX-512) with support of Vector Neural Network Instructions supporting BF16 enabled processors.

Yes

AVX512_E4

Intel® Advanced Vector Extensions 512 (Intel® AVX-512) with Intel® Deep Learning Boost (Intel® DL Boost) and bfloat16 support and Intel® Advanced Matrix Extensions (Intel® AMX) with bfloat16 and 8-bit integer support.

Yes

AVX2

Intel® AVX2

Yes

AVX2_E1

Intel® Advanced Vector Extensions 2 (Intel® AVX2) with support for Intel® Deep Learning Boost (Intel® DL Boost).

Yes

AVX

Intel® AVX

Yes

SSE4_2

Intel® SSE4.2

Yes

For more details about the mkl_enable_instructions function, including the argument values, see the Intel® oneAPI Math Kernel Library Developer Reference.

For example:

  • To turn on automatic CPU-based dispatching of Intel AVX-512 with support of Intel DL Boost, bfloat16, Intel AMX with bfloat16 and 8-bit integer, and FP16 instruction, do one of the following:

    • Call

      mkl_enable_instructions(AVX512_E4)

    • Set the environment variable:

      • For the bash shell:

        export MKL_ENABLE_INSTRUCTIONS=AVX512_E4

      • For a C shell (csh or tcsh):

        setenv MKL_ENABLE_INSTRUCTIONS AVX512_E4

  • To configure the library not to dispatch more recent architectures than Intel AVX2, do one of the following:

    • Call

      mkl_enable_instructions(MKL_ENABLE_AVX2)

    • Set the environment variable:

      • For the bash shell:

        export MKL_ENABLE_INSTRUCTIONS=AVX2

      • For a C shell (csh or tcsh):

        setenv MKL_ENABLE_INSTRUCTIONS AVX2

NOTE:

Settings specified by the mkl_enable_instructions function take precedence over the settings specified by the MKL_ENABLE_INSTRUCTIONS environment variable.

Product and Performance Information

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

Notice revision #20201201

Parent topic: Managing Behavior of the Intel® oneAPI Math Kernel Library with Environment Variables
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