Predecessor/successor approach for high-performance run-time wavefront scheduling

Most scientific applications rely on parallel multiprocessor computing to enhance performance. However, the irregular loops within these applications obstruct the parallelism analysis at compile-time. Rauchwerger et al. presented a run-time method to extract the hidden parallelism in a program using dependence chains. The relative overhead degrades this approach’s performance due to the mass storage requirement and huge array reference processing. In this study, a new predecessor/successor approach is developed in which high-level predecessor/successor information is recorded and processed efficiently. A predecessor/successor table is constructed first in the inspector phase so that only the successor iterations in the current wavefront need to be examined, instead of the entire loop iterations during wavefront scheduling. Usually, the performance of dependence chain approach degrades dramatically for a hot-spot access pattern, but our scheme works very efficiently in this case. The experimental results using synthetic code and real programs are presented to prove the superiority of the proposed approach.