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Issue No. 02 - April (1990 vol. 1)
ISSN: 1045-9219
pp: 218-230
<p>The question of whether prefetching blocks on the file into the block cache can effectively reduce overall execution time of a parallel computation, even under favorable assumptions, is considered. Experiments have been conducted with an interleaved filesystem testbed on the Butterfly Plus multiprocessor. Results of these experiments suggest that (1) the hit ratio, the accepted measure in traditional caching studies, may not be an adequate measure of performance when the workload consists of parallelcomputations and parallel file access patterns, (2) caching with prefetching can significantly improve the hit ratio and the average time to perform an I/O (input/output) operation, and (3) an improvement in overall execution time has been observed in mostcases. In spite of these gains, prefetching sometimes results in increased execution times (a negative result, given the optimistic nature of the study). The authors explore why it is not trivial to translate savings on individual I/O requests into consistently better overall performance and identify the key problems that need to be addressed in order to improve the potential of prefetching techniques in the environment.</p>
Index Termsconcurrent OS; disc caching; file systems; MIMD multiprocessors; execution time; parallel computation; interleaved file system; Butterfly Plus multiprocessor; hit ratio; performance; caching; prefetching; I/O requests; buffer storage; file organisation; multiprocessing systems; performance evaluation

C. Ellis and D. Kotz, "Prefetching in File Systems for MIMD Multiprocessors," in IEEE Transactions on Parallel & Distributed Systems, vol. 1, no. , pp. 218-230, 1990.
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