Out of Context Cache Prefetching

Abstract

This study examines the efficacy of modifying a hardware cache prefetcher to track and predict context switches and prefetch for incoming processes before they are switched in. The study is composed of three major components - quantifying the amount of contextswitches that can be correctly predicted, examining out of context prefetching on CPU-bound processes and I/O-bound processes, and examining the effects of varying how early before a context switch to begin prefetching.Data suggests that highly accurate context switch prediction is viable, with our own simple prediction unit correctly predicting over 75% of context switches. The study shows that out of context prefetching may not work well with CPU-bound processes, as the positive effects are masked by therelatively long timeslice lengths. Finally, performing out of context prefetching on I/O-bound processes exhibits significant performance improvements over traditional cache prefetching.