ExBLAS aims at providing new algorithms and implementations for fundamental linear algebra operations -- like those included in the BLAS library -- that deliver reproducible and accurate results with small or without losses to their performance on modern parallel architectures such as Intel desktop and server processors, Intel Xeon Phi co-processors, and GPU accelerators. We construct our approach in such a way that it is independent from data partitioning, order of computations, thread scheduling, or reduction tree schemes.

The current version of the ExBLAS library is equipped with

• ExSUM -- Reproducible and accurate parallel reduction (parallel summation);
• ExDOT -- Reproducible and accurate parallel dot product;
• ExGEMV -- Reproducible and accurate parallel matrix-vector product for various sizes (m = n, m >= n, and m <= n) for both transpose and non-transpose matrices;
• ExTRSV -- Reproducible and accurate parallel triangular solver for both transpose and non-transpose, lower and unit triangular matrices with unit and non-unit diagonals;
• ExGEMM -- Reproducible and accurate parallel matrix-matrix multiplication for squeare matrices for a moment. These routines can be executed on a set of architectures: Intel Core i7 and Sandy Bridge processors; Intel Xeon Phi co-processors; both AMD and NVIDIA GPUs using the OpenCL framework.

In order to use ExBLAS, the following software is needed:

• [Required] Cmake of version 2.8.8 or higher
• [Required] For CPUs, support of AVX instructions
• [Required] For CPUs, Intel TBB library of version 4.0 or higher
• [Required] For CPUs, support of C++11
• [Required] For MIC, Intel C/C++ compilers
• [Required] For GPUs only, OpenCL of version 1.1 or higher
• [Optional] GMP of version 6.0
• [Optional] MPFR of version 3.1.2 The later two are required to verify the accuracy and reproducibility of the results.

• Download the latest version of source code from exblas.lip6.fr
• Extract the sources from a tar.gz archive (tar -zxvf) to {EXBLAS_ROOT} folder
• Create a build dir in the root of the library and move there

• -DEXBLAS_MPI=ON -- enables compilation with MPI. By default, only shared-memory parallelism is activated
• -DEXBLAS_MIC=ON -- enables compilation for Intel MIC architectures
• -DEXBLAS_GPU=ON -- enables compilation for GPUs -DEXBLAS_GPU_AMD=ON -- for AMD GPUs -DEXBLAS_GPU_NVIDIA=ON -- for NVIDIA GPUs
• -DEXBLAS_VS_MPFR=ON -- compares the results against the ones produced by MPFR

• For Intel CPU with AVX instructions: CC=icc CXX=icpp cmake .. make make install

• With MPI: CC=mpicc CXX=mpicxx cmake -DEXBLAS_MPI=ON .. make make install

• For GPU: CC=mpicc CXX=mpicxx cmake -DEXBLAS_GPU=ON -DEXBLAS_AMD|NVIDIA_GPU=ON .. make make install

• For MIC: CC=mpicc CXX=mpicxx cmake -DEXBLAS_MIC=ON .. make make install

• make test -- it will run several tests using naive, loguniform, and ill-cond number distribution comparing the results either against the ones produced by superaccumulators only or by MPFR

• All tests are stored in the tests dir

• [Required] Doxygen of version 1.8.0

• [Optional] LaTeX in case you want to generate documentation in pdf format

• -DEXBLAS_DOC=ON -- enables generationg of the ExBLAS documentation using Doxygen and LaTeX

• make doc -- command to generate an html version of the ExBLAS documentation

• make pdf -- command to generate a pdf version of the ExBLAS documentation

In the example dir you can find a simple test that shows how the ExBLAS routines can be called and how the ExBLAS library can be linked from your project.