Optimizing parallel GEMM routines using auto-tuning with Intel AVX-512

This paper presents the optimal implementations of single-and double-precision general matrix-matrix multiplication (GEMM) routines for the Intel Xeon Phi Processor code-named Knights Landing (KNL) and the Intel Xeon Scalable Processors based on an auto-tuning approach with the Intel AVX-512 intrinsic functions. Our auto-tuning approach precisely determines the parameters reflecting the target architectural features. Our approach significantly reduces the search space and derives optimal parameter sets including the size of submatrices, prefetch distances, loop unrolling depth, and parallelization scheme. Without a single line of assembly code, our GEMM kernels show the comparable performance results to the Intel MKL and outperform other open-source BLAS libraries.