Static caching in Web servers

Abstract

This paper studies caching in primary Web servers. We use log files from four Web servers to analyze the performance of various proposed cache policies for Web servers: LRU-threshold, LFU, LRU-SIZE, LRU-MIN, LRU-k-threshold and the Pitkow/Recker (1994) policy. Web document access patterns change very slowly. Based on this fact, we propose and evaluate static caching, a novel cache policy for Web servers. In static caching, the set of documents kept in the cache is determined periodically by analyzing the request log file for the previous period. The cache is filled with documents to maximize cache performance provided document access patterns do not change. The set of cached documents remains constant during the period. Surprisingly, this simple policy results in high cache performance, especially for small cache sizes. Unlike other policies, static caching incur no CPU overhead and does not suffer from memory fragmentation.