OpenBLAS

Introduction

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

Please read the documents on OpenBLAS wiki pages http://github.com/xianyi/OpenBLAS/wiki.

Binary Packages

We provide 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. http://xianyi.github.com/OpenBLAS/

Or, check out codes from git://github.com/xianyi/OpenBLAS.git

Normal compile

• type "make" to detect the CPU automatically. or
• type "make TARGET=xxx" to set target CPU, e.g. "make TARGET=NEHALEM". The full target list is in file TargetList.txt.

Cross compile

Please set CC and FC with the cross toolchains. Then, set HOSTCC with your host C compiler. At last, set TARGET explicitly.

Examples:

On X86 box, compile this library for loongson3a CPU.

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

On X86 box, compile this library for 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

make DEBUG=1

Install to the directory (optional)

Example:

make install PREFIX=your_installation_directory

The default directory is /opt/OpenBLAS

Support CPU & OS

Please read GotoBLAS_01Readme.txt

Additional support CPU:

x86/x86-64:

• Intel Xeon 56xx (Westmere): Used GotoBLAS2 Nehalem codes.
• Intel Sandy Bridge: Optimized Level-3 BLAS with AVX on x86-64.
• Intel Haswell: Optimized Level-3 BLAS with AVX on x86-64 (identical to Sandy Bridge).
• AMD Bobcat: Used GotoBLAS2 Barcelona codes.
• AMD Bulldozer: x86-64 S/DGEMM AVX kernels. (Thank Werner Saar)
• AMD PILEDRIVER: Used Bulldozer codes.

MIPS64:

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

Support OS:

• GNU/Linux
• MingWin/Windows: Please read https://github.com/xianyi/OpenBLAS/wiki/How-to-use-OpenBLAS-in-Microsoft-Visual-Studio.
• Darwin/Mac OS X: Experimental. Although GotoBLAS2 supports Darwin, we are the beginner on Mac OS X.
• FreeBSD: Supported by community. We didn't test the library on this OS.

Usages

Link with libopenblas.a or -lopenblas for shared library.

Set the number of threads with environment variables.

Examples:

export OPENBLAS_NUM_THREADS=4

or

export GOTO_NUM_THREADS=4

or

export OMP_NUM_THREADS=4

The priorities are OPENBLAS_NUM_THREADS > GOTO_NUM_THREADS > OMP_NUM_THREADS.

If you compile this lib with USE_OPENMP=1, you should set OMP_NUM_THREADS environment variable. OpenBLAS ignores OPENBLAS_NUM_THREADS and GOTO_NUM_THREADS with USE_OPENMP=1.

Set the number of threads on runtime.

We provided the below functions to control the number of threads on runtime.

void goto_set_num_threads(int num_threads);

void openblas_set_num_threads(int num_threads);

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

Report Bugs

Please add a 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

ChangeLog

Please see Changelog.txt to obtain the differences between GotoBLAS2 1.13 BSD version.

Troubleshooting

• Please read Faq at 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. The Clang 3.0 will generate the wrong AVX binary code.
• The number of CPUs/Cores should less than or equal to 256.
• On Linux, OpenBLAS sets the processor affinity by default. This may cause the conflict with R parallel. You can build the library with NO_AFFINITY=1.
• On Loongson 3A. make test would be failed because of pthread_create error. The error code is EAGAIN. However, it will be OK when you run the same testcase on 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.