Another view on parallel speedup

In this paper three models of parallel speedup are studied. They are fixed-size speedup, fixed-time speedup and memory-bounded speedup. Two sets of speedup formulations are derived for these three models. One set requires more information and gives more accurate estimation. Another set considers a simplified case and provides a clear picture of possible performance gain of parallel processing. The simplified fixed-size speedup is Amdahl's law. The simplified fixed-time speedup is Gustafson's scaled speedup. The simplified memory-bounded speedup contains both Amdahl's law and Gustafson's scaled speedup as its special cases. This study proposes a new metric for performance evaluation and leads to a better understanding of parallel processing.