Dipl.-Math. Martin Köhler
Dipl.-Math. Martin Köhler
Phone: +49 391 6110 445
Fax: +49 391 6110 453
Dr. Jens Saak
Dr. Jens Saak
Phone: +49 391 6110 216
Fax: +49 391 6110 453


FlexiBLAS - A BLAS wrapper library with runtime exchangable backends

FlexiBLAS - A BLAS wrapper library with runtime exchangable backends

The BLAS library is one of the central libraries for the implementation of numerical algorithms. It serves as the basis for many other numerical libraries like LAPACK, PLASMA or MAGMA (to mention only the most obvious). Thus a fast BLAS implementation is the key ingredient for efficient  applications in this area. However, for debugging or benchmarking purposes it is often necessary to replace the underlying BLAS implementation of an application, e.g. to disable threading or to include  debugging symbols. We present a novel  framework that allows one to exchange the BLAS implementation at   run-time via an environment variable. Our concept neither requires relinkage, nor recompilation of the application. Numerical experiments show that there is no notable overhead introduced by this new approach. For only a very little overhead the framework naturally extends to a minimal profiling setup that allows one to count numbers of calls to the BLAS routines used and measure the time spent therein.

Main Features

  • Runtime exchangable BLAS and LAPACK backend without recompilation of any software.
  • Supports all BLAS functions and al LAPACK functions from Version 3.7.0 with an 100% BLAS and LAPACK compatible ABI/API.
  • Flexible per system/per user/per host configuration files.
  • Integration of user-owned BLAS libraries without administrator priviledges even in system wide installed programs.
  • Interface for GNU Octave to change the BLAS backend at runtime.
  • Basic profiling support.
  • Works with NETLIB-BLAS, OpenBLAS, ATLAS, Intel MKL, ACML, ...
  • Aware of 32-bit and 64-bit integers
  • Works on Linux and *BSD.

Planed Features / In Development

  • Overloading of BLAS and LAPACK functions for debugging purpose.
  • Profile and trace backend to log all BLAS calls.
  • Replay functionality to simulate all BLAS calls with different BLAS implementations.
  • GPU offloading backend to accelerate BLAS calls on GPU enabled systems.
  • Continuous import of new LAPACK versions. (LAPACK 3.8.0 support will release with the next version of FlexiBLAS)


Version 2.0.0

Older versions:

Public git repository:

Recent Changes

From version 2.0.0 FlexiBLAS supports:

  • All LAPACK routines included up to LAPACK Version 3.7.0
  • per host user settings

Installation Instructions

Simply download the source tarball and follow the steps described in the file therein. Alternatively, you can check the Installation Instructions page for a method with better integration into your systems package management.

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