Optimization of Lattice QCD codes for the AMD Opteron processor

Lattice QCD is a powerful method to study Quantum chromodynamics (QCD) in a nonperturbative way. In lattice QCD, a path integral is directly evaluated on a discrete space-time lattice by means of the Monte Carlo method. As computer technology advances PC clusters can also be used for lattice QCD simulations as well as a number of commercial supercomputers. Since lattice QCD simulations demand huge computer power, it is very important to optimize the simulation codes so as to exploit the full potential of the processor. Thus we optimize the hot spots of the codes such as the operation of a Dirac operator to a spinor (referred as Qφ hereafter) and linear algebra of spinors, e.g.