Exposing I/O Concurrency with Informed Prefetching
Appears in Proc. of Third Int'l. Conf. on Parallel and Distributed Information Systems, Austin, TX, September 28-30, 1994, pp.7-16.
R. Hugo Patterson, Garth A. Gibson
School of Computer Science
Carnegie Mellon University
Pittsburgh, PA 15213
Informed prefetching provides a simple mechanism for I/O-intensive, cache-ineffective applications to efficiently exploit highly-parallel I/O subsystems such as disk arrays. This mechanism, dynamic disclosure of future accesses, yields substantial benefits over sequential readahead mechanisms found in current file systems for non-sequen tial workloads. This paper reports the performance of the Transparent Informed Prefetching system (TIP), a minimal prototype implemented in a Mach 3.0 system with up to four disks. We measured reductions by factors of up to 1.9 and 3.7 in the execution time of two example applications: multi-file text search and scientific data visualization.