OpenBLAS

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Introduction

OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version.

Please read the documentation on the OpenBLAS wiki pages: https://github.com/xianyi/OpenBLAS/wiki.

Binary Packages

We provide official binary packages for the following platform:

• Windows x86/x86_64

You can download them from file hosting on sourceforge.net.

Installation from Source

Download from project homepage, https://xianyi.github.com/OpenBLAS/, or check out the code using Git from https://github.com/xianyi/OpenBLAS.git.

Dependencies

Building OpenBLAS requires the following to be installed:

• GNU Make
• A C compiler, e.g. GCC or Clang
• A Fortran compiler (optional, for LAPACK)
• IBM MASS (optional, see below)

Normal compile

Simply invoking make (or gmake on BSD) will detect the CPU automatically. To set a specific target CPU, use make TARGET=xxx, e.g. make TARGET=NEHALEM. The full target list is in the file TargetList.txt.

Cross compile

Set CC and FC to point to the cross toolchains, and set HOSTCC to your host C compiler. The target must be specified explicitly when cross compiling.

Examples:

• On an x86 box, compile this library for a loongson3a CPU:

  make BINARY=64 CC=mips64el-unknown-linux-gnu-gcc FC=mips64el-unknown-linux-gnu-gfortran HOSTCC=gcc TARGET=LOONGSON3A

• On an x86 box, compile this library for a loongson3a CPU with loongcc (based on Open64) compiler:

  make CC=loongcc FC=loongf95 HOSTCC=gcc TARGET=LOONGSON3A CROSS=1 CROSS_SUFFIX=mips64el-st-linux-gnu-   NO_LAPACKE=1 NO_SHARED=1 BINARY=32

Debug version

A debug version can be built using make DEBUG=1.

Compile with MASS support on Power CPU (optional)

The IBM MASS library consists of a set of mathematical functions for C, C++, and Fortran applications that are tuned for optimum performance on POWER architectures. OpenBLAS with MASS requires a 64-bit, little-endian OS on POWER. The library can be installed as shown:

• On Ubuntu:

  wget -q http://public.dhe.ibm.com/software/server/POWER/Linux/xl-compiler/eval/ppc64le/ubuntu/public.gpg -O- | sudo apt-key add -
  echo "deb http://public.dhe.ibm.com/software/server/POWER/Linux/xl-compiler/eval/ppc64le/ubuntu/ trusty main" | sudo tee /etc/apt/sources.list.d/ibm-xl-compiler-eval.list
  sudo apt-get update
  sudo apt-get install libxlmass-devel.8.1.5

• On RHEL/CentOS:

  wget http://public.dhe.ibm.com/software/server/POWER/Linux/xl-compiler/eval/ppc64le/rhel7/repodata/repomd.xml.key
  sudo rpm --import repomd.xml.key
  wget http://public.dhe.ibm.com/software/server/POWER/Linux/xl-compiler/eval/ppc64le/rhel7/ibm-xl-compiler-eval.repo
  sudo cp ibm-xl-compiler-eval.repo /etc/yum.repos.d/
  sudo yum install libxlmass-devel.8.1.5

After installing the MASS library, compile OpenBLAS with USE_MASS=1. For example, to compile on Power8 with MASS support: make USE_MASS=1 TARGET=POWER8.

Install to a specific directory (optional)

Use PREFIX= when invoking make, for example

make install PREFIX=your_installation_directory

The default installation directory is /opt/OpenBLAS.

Supported CPUs and Operating Systems

Please read GotoBLAS_01Readme.txt.

Additional supported CPUs

x86/x86-64

• Intel Xeon 56xx (Westmere): Used GotoBLAS2 Nehalem codes.
• Intel Sandy Bridge: Optimized Level-3 and Level-2 BLAS with AVX on x86-64.
• Intel Haswell: Optimized Level-3 and Level-2 BLAS with AVX2 and FMA on x86-64.
• Intel Skylake: Optimized Level-3 and Level-2 BLAS with AVX512 and FMA on x86-64.
• AMD Bobcat: Used GotoBLAS2 Barcelona codes.
• AMD Bulldozer: x86-64 ?GEMM FMA4 kernels. (Thanks to Werner Saar)
• AMD PILEDRIVER: Uses Bulldozer codes with some optimizations.
• AMD STEAMROLLER: Uses Bulldozer codes with some optimizations.
• AMD ZEN: Uses Haswell codes with some optimizations.

MIPS64

• ICT Loongson 3A: Optimized Level-3 BLAS and the part of Level-1,2.
• ICT Loongson 3B: Experimental

ARM

• ARMv6: Optimized BLAS for vfpv2 and vfpv3-d16 (e.g. BCM2835, Cortex M0+)
• ARMv7: Optimized BLAS for vfpv3-d32 (e.g. Cortex A8, A9 and A15)

ARM64

• ARMv8: Experimental
• ARM Cortex-A57: Experimental

PPC/PPC64

• POWER8: Optimized BLAS, only for PPC64LE (Little Endian), only with USE_OPENMP=1
• POWER9: Optimized Level-3 BLAS (real) and some Level-1,2. PPC64LE with OpenMP only.

IBM zEnterprise System

• Z13: Optimized Level-3 BLAS and Level-1,2 (double precision)
• Z14: Optimized Level-3 BLAS and Level-1,2 (single precision)

Supported OS

• GNU/Linux
• MinGW or Visual Studio (CMake)/Windows: Please read https://github.com/xianyi/OpenBLAS/wiki/How-to-use-OpenBLAS-in-Microsoft-Visual-Studio.
• Darwin/macOS: Experimental. Although GotoBLAS2 supports Darwin, we are not macOS experts.
• FreeBSD: Supported by the community. We don't actively test the library on this OS.
• OpenBSD: Supported by the community. We don't actively test the library on this OS.
• DragonFly BSD: Supported by the community. We don't actively test the library on this OS.
• Android: Supported by the community. Please read https://github.com/xianyi/OpenBLAS/wiki/How-to-build-OpenBLAS-for-Android.

Usage

Statically link with libopenblas.a or dynamically link with -lopenblas if OpenBLAS was compiled as a shared library.

Setting the number of threads using environment variables

Environment variables are used to specify a maximum number of threads. For example,

export OPENBLAS_NUM_THREADS=4
export GOTO_NUM_THREADS=4
export OMP_NUM_THREADS=4

The priorities are OPENBLAS_NUM_THREADS > GOTO_NUM_THREADS > OMP_NUM_THREADS.

If you compile this library with USE_OPENMP=1, you should set the OMP_NUM_THREADS environment variable; OpenBLAS ignores OPENBLAS_NUM_THREADS and GOTO_NUM_THREADS when compiled with USE_OPENMP=1.

Setting the number of threads at runtime

We provide the following functions to control the number of threads at runtime:

void goto_set_num_threads(int num_threads);
void openblas_set_num_threads(int num_threads);

If you compile this library with USE_OPENMP=1, you should use the above functions too.

Reporting bugs

Please submit an issue in https://github.com/xianyi/OpenBLAS/issues.

Contact

• OpenBLAS users mailing list: https://groups.google.com/forum/#!forum/openblas-users
• OpenBLAS developers mailing list: https://groups.google.com/forum/#!forum/openblas-dev

Change log

Please see Changelog.txt to view the differences between OpenBLAS and GotoBLAS2 1.13 BSD version.

Troubleshooting

• Please read the FAQ first.
• Please use GCC version 4.6 and above to compile Sandy Bridge AVX kernels on Linux/MinGW/BSD.
• Please use Clang version 3.1 and above to compile the library on Sandy Bridge microarchitecture. Clang 3.0 will generate the wrong AVX binary code.
• Please use GCC version 6 or LLVM version 6 and above to compile Skylake AVX512 kernels.
• The number of CPUs/cores should less than or equal to 256. On Linux x86_64 (amd64), there is experimental support for up to 1024 CPUs/cores and 128 numa nodes if you build the library with BIGNUMA=1.
• OpenBLAS does not set processor affinity by default. On Linux, you can enable processor affinity by commenting out the line NO_AFFINITY=1 in Makefile.rule. However, note that this may cause a conflict with R parallel.
• On Loongson 3A, make test may fail with a pthread_create error (EAGAIN). However, it will be okay when you run the same test case on the shell.

Contributing

1. Check for open issues or open a fresh issue to start a discussion around a feature idea or a bug.
2. Fork the OpenBLAS repository to start making your changes.
3. Write a test which shows that the bug was fixed or that the feature works as expected.
4. Send a pull request. Make sure to add yourself to CONTRIBUTORS.md.

Donation

Please read this wiki page.