Amortized efficiency of list update and paging rules
Communications of the ACM
The Harvest information discovery and access system
Computer Networks and ISDN Systems
Serverless network file systems
SOSP '95 Proceedings of the fifteenth ACM symposium on Operating systems principles
Distributed paging for general networks
Proceedings of the seventh annual ACM-SIAM symposium on Discrete algorithms
Placement algorithms for hierarchical cooperative caching
Journal of Algorithms
An adaptive, non-uniform cache structure for wire-delay dominated on-chip caches
Proceedings of the 10th international conference on Architectural support for programming languages and operating systems
Developments from a June 1996 seminar on Online algorithms: the state of the art
A tight bound on approximating arbitrary metrics by tree metrics
Proceedings of the thirty-fifth annual ACM symposium on Theory of computing
Probabilistic approximation of metric spaces and its algorithmic applications
FOCS '96 Proceedings of the 37th Annual Symposium on Foundations of Computer Science
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We address a hierarchical generalization of the well-known disk paging problem. In the hierarchical cooperative caching problem, a set of n machines residing in an ultrametric space cooperate with one another to satisfy a sequence of read requests to a collection of (read-only) files. A seminal result in the area of competitive analysis states that LRU (the widely-used deterministic online paging algorithm based on the "least recently used" eviction policy) is constant-competitive if it is given a constant-factor blowup in capacity over the offline algorithm. Does such a constant-competitive deterministic algorithm (with a constant-factor blowup in the machine capacities) exist for the hierarchical cooperative caching problem? The main contribution of the present paper is to answer this question in the negative. More specifically, we establish an Ω(log log n) lower bound on the competitive ratio of any online hierarchical cooperative caching algorithm with capacity blowup O((log n)1-ε), where ε denotes an arbitrarily small positive constant.