OpenBLAS

Introduction

OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version. OpenBLAS is an open source project supported by Lab of Parallel Software and Computational Science, ISCAS http://www.rdcps.ac.cn.

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

Installation

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

Debug version

make DEBUG=1

Intall 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.
• AMD Bobcat: Used GotoBLAS2 Barcelona codes.
• AMD Bulldozer: Used GotoBLAS2 Barcelona 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: Supportted 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 controll the number of threads on runtime. So far, we didn't support changing the number of threads on Windows. On Windows, these functions are dummy.

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: http://list.rdcps.ac.cn/mailman/listinfo/openblas

ChangeLog

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

Troubleshooting

• 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.

Specification of Git Branches

We used the git branching model in this article (http://nvie.com/posts/a-successful-git-branching-model/). Now, there are 4 branches in github.com.

• The master branch. This a main branch to reflect a production-ready state.
• The develop branch. This a main branch to reflect a state with the latest delivered development changes for the next release.
• The loongson3a branch. This is a feature branch. We develop Loongson3A codes on this branch. We will merge this feature to develop branch in future.
• The gh-pages branch. This is for web pages