A Trace-Driven Comparison of Algorithms for Multi-Process Prefetching and Caching

Recently two groups of researchers have proposed systems that exploit application knowledge to improve I/O performance. Both systems use application knowledge to prefetch data thereby masking I/O latency and to improve file buffer cache performance thereby avoiding slow I/O accesses altogether. Unfortunately, published studies of these two systems are incomparable. This technical report is a follow-on to a paper to appear in OSDI96 comparing the TIP2 system of Patterson, Gibson, et al, and the LRU-SP system of Cao, Felten, Karlin and Li, co-written by the two groups. The OSDI paper considers the case of a single process with full advance knowledge of requests. In this technical report we consider multiple processes, each of which has either full advance knowledge (complete hints) or no advance knowledge (no hints). Our results can be summarized as follows: the cost-benefit analysis of TIP2 allows better performance when optimal buffer allocation does not correspond to process consumpti..