Asymptotic Insensitivity of Least-Recently-Used Caching to Statistical Dependency

Abstract— We investigate a widely popular Least-RecentlyUsed (LRU) cache replacement algorithm with semi-Markov modulated requests. Semi-Markov processes provide the flexibility for modeling strong statistical correlation, including the broadly reported long-range dependence in the World Wide Web page request patterns. When the frequency of requesting a page n is equal to the generalized Zipf’s law c/nα , α > 1, our main result shows that the cache fault probability is asymptotically, for large cache sizes, the same as in the corresponding LRU system with i.i.d. requests. This appears to be the first explicit average case analysis of LRU caching with statistically dependent request sequences. The surprising insensitivity of LRU caching performance demonstrates its robustness to changes in document popularity. Furthermore, we show that the derived asymptotic result and simulation experiments are in excellent agreement, even for relatively small cache sizes. The potential of u...

• Type: Conference
• Year: 2003
• Where: INFOCOM
• Authors: Predrag R. Jelenkovic, Ana Radovanovic
• Keywords: Cache, Cache Replacement Algorithm, Cache Sizes, Communications, INFOCOM 2003