  Stencil computations consume a major part of runtime in many scientific
simulation codes. As prototypes for this class of algorithms we consider the
iterative Jacobi and Gauss-Seidel smoothers and aim at highly efficient
parallel implementations for cache-based multicore architectures. Temporal
cache blocking is a known advanced optimization technique, which can reduce the
pressure on the memory bus significantly. We apply and refine this optimization
for a recently presented temporal blocking strategy designed to explicitly
utilize multicore characteristics. Especially for the case of Gauss-Seidel
smoothers we show that simultaneous multi-threading (SMT) can yield substantial
performance improvements for our optimized algorithm.
