The Compression Cache: Using On-line Compression to Extend Physical Memory.

Abstract

This paper describes a method for trading off computation for disk or network I/O by using less expensive on-line compression. By using some memory to store data in compressed format, it may be possible to fit the working set of one or more large applications in relatively small memory. For working sets that are too large to fit in memory even when compressed, compression still provides a benefit by reducing bandwidth and space requirements. Overall, the effectiveness of this compression cache depends on application behavior and the relative costs of compression and I/O. Measurements using Sprite on a DECstation 1 5000/200 workstation with a local disk indicate that some memory-intensive applications running with a compression cache can run two to three times faster than on an unmodified system. Better speedups would be expected in a system with a greater disparity between the speed of its processor and the bandwidth to its backing store. 1 Introduction Over the past decade, the pr...