Simulating Galaxy Formation on SMPS

We discuss the implementation of HYDRA, a combined hydrodynamic and gravity N-body particle integrator, on shared memory architectures with a symmetric multi-processor configuration (SMP). Parallelization is achieved using the parallelization directives in the MIPSpro Fortran 77 instruction set. We examine the performance of the code and find excellent scaling up to 8 processors. The maximum number of process elements is limited by race conditions which are difficult to overcome. The new code takes advantage of the considerable processing power of mid-range machines and permits simulations of a scale lying between those attempted on workstations and massively parallel supercomputers.