Adaptive Aggregation Based Domain Decomposition Multigrid for the Lattice Wilson Dirac Operator

Abstract. In lattice QCD computations a substantial amount of work is spent in solving linear systems arising in Wilson’s discretization of the Dirac equations. We show first numerical results of the extension of the two-level DD-αAMG method to a true multilevel method based on our parallel MPI-C implementation. Using additional levels pays off, allowing to cut down the core minutes spent on one system solve by a factor of approximately 700 compared to standard Krylov subspace methods and yielding another speed-up of a factor of 1.7 over the two-level approach