A persistent rescheduled-page cache for low overhead object code compatibility in VLIW architectures
Thomas M. Conte, Sumedh W. Sathaye, Sanjeev Banerjia · 1996
Object-code compatibility between processor generations is an open issuefor VLIW architectures. A potentialsolution is a technique termed dynamic rescheduling, which performs run-time software rescheduling at the$rst-time page faults. The time required for rescheduling the pages constitutes a large portion of the overhead of this method. A disk caching scheme that uses a persistent rescheduled-page cache (PRC) is presented. The scheme reduces the overhead associated with dynamic rescheduling by saving rescheduled pages on disk, across program executions. Operating system sup-port is required for dynamic rescheduling and management of the PRC. The implementation details for the PRC are discussed. Results of simulations used to gauge the effec-tiveness of PRC indicate that (I) the PRC is effective in reducing the overhead of dynamic rescheduling, and (2) due to different overhead requirements ofprograms, a split PRC organization performs better than a unified PRC. The unified PRC was studied for two different page re-placement policies: LRU and overhead-based replacement. It was found that with LRU replacement, all the programs consistently perform better with increasing PRC sizes, but the high-overhead programs take a consistent performance hit compared to the low-overhead programs. With overhead-based replacement, the per$ormance of high-overhead pro-grams improves substantially, while the low-overhead pro-grams perform only slightly worse than in the case of the LRU replacement. 1