Cache pollution in Web proxy servers

Caching has been used for decades as an effective performance enhancing technique in computer systems. The Least Recently Used (LRU) cache replacement algorithm is a simple and widely used scheme. Proxy caching is a common approach to reduce network traffic and delay in many World Wide Web (WWW) applications. However, some characteristics of WWW workloads make LRU less attractive in proxy caching. In the recent years, several more efficient replacement algorithms have been suggested. But, these advanced algorithms require a lot of knowledge about the workloads and are generally difficult to implement. The main attraction of LRU is its simplicity. In this paper we present two modified LRU algorithms and compare their performance with the LRU. Our results indicate that the performance of the LRU algorithm can be improved substantially with very simple modifications.