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BLASFEO - BLAS For Embedded Optimization

BLASFEO provides a set of basic linear algebra routines, performance-optimized for matrices that fit in cache (i.e. generally up to a couple hundred size in each dimension), as typically encountered in embedded optimization applications.

Supported Computer Architectures

The architecture for BLASFEO to use is specified using the TARGET build variable. Currently BLASFEO supports the following architectures:

TARGET Description
X64_INTEL_HASWELL Intel Haswell architecture or newer, AVX2 and FMA ISA, 64-bit OS
X64_INTEL_SANDY_BRIDGE Intel Sandy-Bridge architecture or newer, AVX ISA, 64-bit OS
X64_INTEL_CORE Intel Core architecture or newer, SSE3 ISA, 64-bit OS
X64_AMD_BULLDOZER AMD Bulldozer architecture, AVX and FMA ISAs, 64-bit OS
X86_AMD_JAGUAR AMD Jaguar architecture, AVX ISA, 32-bit OS
X86_AMD_BARCELONA AMD Barcelona architecture, SSE3 ISA, 32-bit OS
ARMV8A_ARM_CORTEX_A57 ARMv8A architecture, VFPv4 and NEONv2 ISAs, 64-bit OS
ARMV8A_ARM_CORTEX_A53 ARMv8A architecture, VFPv4 and NEONv2 ISAs, 64-bit OS
ARMV7A_ARM_CORTEX_A15 ARMv7A architecture, VFPv3 and NEON ISAs, 32-bit OS
ARMV7A_ARM_CORTEX_A7 ARMv7A architecture, VFPv3 and NEON ISAs, 32-bit OS
GENERIC Generic target, coded in C, giving better performance if the architecture provides more than 16 scalar FP registers (e.g. many RISC such as ARM)

Note that the X86_AMD_JAGUAR and X86_AMD_BARCELONA architectures are not supported by the CMake build system and can only be used through the included Makefile.

Automatic Target Detection

When using the CMake build system, it is possible to automatically detect the X64 target the current computer can use. This can be enabled by specifying the X64_AUTOMATIC target. In this mode, the build system will automatically search through the X64 targets to find the best one that can both compile and run on the host machine.

Target Testing

When using the CMake build system, tests will automatically be performed to see if the current compiler can compile the needed code for the selected target and that the current computer can execute the code compiled for the current target. The execution test can be disabled by setting the BLASFEO_CROSSCOMPILING flag to true. This is automatically done when CMake detects that cross compilation is happening.

Linear Algebra Routines

The BLASFEO backend provides three possible implementations of each linear algebra routine, specified using the LA build variable:

LA Description
HIGH_PERFORMANCE Target-tailored; performance-optimized for cache resident matrices; panel-major matrix format. Currently provided for OS_LINUX (x86_64 64-bit, x86 32-bit, ARMv8A 64-bit, ARMv7A 32-bit), OS_WINDOWS (x86_64 64-bit) and OS_MAC (x86_64 64-bit).
REFERENCE Target-unspecific lightly-optimizated; small code footprint; column-major matrix format
EXTERNAL_BLAS_WRAPPER Call to external BLAS and LAPACK libraries; column-major matrix format

BLASFEO APIs

BLASFEO provides two APIs:

  • BLAS API: the standard BLAS and LAPACK APIs, with matrices stored in column-major.
  • BLASFEO API: this API is optimized to reduce overhead for small matrices. It employes structures to describe matrices (blasfeo_dmat) and vectors (blasfeo_dvec), defined in include/blasfeo_common.h. The actual implementation of blasfeo_dmat and blasfeo_dvec depends on the LA and TARGET choice. The API is non-destructive, and compared to the BLAS API it has an additional matrix/vector argument reserved for the output.

Recommended guidelines

Guidelines to use of BLASFEO routines and avoid known performance issues can be found in the file guidelines.md.
We strongly recommend the user to read it.

More Information

More information can be found on the BLASFEO wiki at https://blasfeo.syscop.de, including more detailed installation instructions, examples, and a rich collection of benchmarks and comparisions.

More scientific information can be found in:

Notes

  • BLASFEO is released under the GPL+CE (Gnu General Public License version 3.0 with Classpath Exception). This license has been chosen to avoid the issues that the LGPL license implies in case of static linking. Unformally speaking, the GPL+CE license allows the BLASFEO library to be linked to both statically and dynamically to produce an executable, and the resulting executable can be released under terms of your choice. Please refer to the LICENSE.txt file for the legally binding statement of the license.

  • 06-01-2018: BLASFEO employs now a new naming convention. The bash script change_name.sh can be used to automatically change the source code of any software using BLASFEO to adapt it to the new naming convention.

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