An evaluation of data-parallel compiler support for line-sweep applications

Data parallel compilers have long aimed to equal the performance of carefully hand-optimized parallel codes. For tightly coupled applications based on line sweeps, this goal has been particularly elusive. In the Rice dHPF compiler, we have developed a wide spectrum of optimizations that enable us to closely approach hand-coded performance for tightly-coupled line sweep applications including the NAS SP and BT benchmark codes. From lightly modified copies of standard serial versions of these benchmarks, dHPF generates MPI-based parallel code that is within 4% of the performance of the hand-crafted MPI implementations of these codes for a 102³ problem size (Class B) on 64 processors. We describe and quantitatively evaluate the impact of partitioning, communication and memory hierarchy optimizations implemented by dHPF that enable us to approach hand-coded performance with compiler-generated parallel code.