Optimization of the Brillouin operator on the KNL architecture

Abstract

Experiences with optimizing the matrix-times-vector application of the Brillouin operator on the Intel KNL processor are reported. Without adjustments to the memory layout, performance figures of 360 Gflop/s in single and 270 Gflop/s in double precision are observed. This is with N_c=3 colors, N_v=12 right-hand-sides, N_{thr}=256 threads, on lattices of size 32^3*64, using exclusively OMP pragmas. Interestingly, the same routine performs quite well on Intel Core i7 architectures, too. Some observations on the much harder Wilson fermion matrix-times-vector optimization problem are added.