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-When bli_pba_acquire_m api is used for packbuf type BLIS_BUFFER_FOR_ <A_BLOCK|B_PANEL|C_PANEL>, the memory is allocated by checking out a block from an internal memory pool. In order to ensure thread safety, the memory pool checkout is protected using mutex (bli_pba_lock/ bli_pba_unlock). When the number of threads trying to checkout memory (in parallel) are high, these locks tend to become a scaling bottleneck, especially when the memory is to be used for non-packing purposes (packing could hide some of this cost). LPGEMM uses bli_pba_acquire_m with BLIS_BUFFER_FOR_C_PANEL to checkout memory when downscale is enabled for temporary C accumulation. This multi-threaded lock overhead becomes prominent when m/n dimensions are relatively small, even when k is large. In order to address this, bli_pba_acquire_m is used with BLIS_BUFFER_FOR_GEN_USE for LPGEMM. For *GEN_USE, the memory is allocated using aligned malloc instead of checking out from memory pool. Experiments have shown malloc costs to be far lower than memory pool guarded by locks, especially for higher thread count. -LPGEMM bench fixes for crash observed when benchmarking with post-ops enabled and no downscale. AMD-Internal: [SWLCSG-2354] Change-Id: I4e92feadd2cf638bb26dd03b773556800a1a3d50
AOCL-BLAS library
AOCL-BLAS is AMD's optimized version of BLAS targeted for AMD EPYC and Ryzen CPUs. It is developed as a forked version of BLIS (https://github.com/flame/blis), which is developed by members of the Science of High-Performance Computing (SHPC) group in the Institute for Computational Engineering and Sciences at The University of Texas at Austin and other collaborators (including AMD). All known features and functionalities of BLIS are retained and supported in AOCL-BLAS library. AOCL-BLAS is regularly updated with the improvements from the upstream repository.
AOCL BLAS is optimized with SSE2, AVX2, AVX512 instruction sets which would be enabled based on the target Zen architecture using the dynamic dispatch feature. All prominent Level 3, Level 2 and Level 1 APIs are designed and optimized for specific paths targeting different size spectrums e.g., Small, Medium and Large sizes. These algorithms are designed and customized to exploit the architectural improvements of the target platform.
For detailed instructions on how to configure, build, install, and link against AOCL-BLAS on AMD CPUs, please refer to the AOCL User Guide located on AMD developer portal.
The upstream repository (https://github.com/flame/blis) contains further information on BLIS, including background information on BLIS design, usage examples, and a complete BLIS API reference.
AOCL-BLAS is developed and maintained by AMD. You can contact us on the email-id toolchainsupport@amd.com. You can also raise any issue/suggestion on the git-hub repository at https://github.com/amd/blis/issues.