STRONGLY COMPETITIVE ALGORITHMS FOR PAGING WITH LOCALITY OF REFERENCE

摘要

What is the best paging algorithm if one has partial information about the possible sequences of page requests? We give a partial answer to this question by presenting the analysis of strongly competitive paging algorithms in the access graph model. This model restricts page requests so that they conform to a notion of locality of reference given by an arbitrary access graph. We first consider optimal algorithms for undirected access graphs. Borodin et al. [Proc. 23rd ACM Symposium on Theory of Computing, 1991, pp. 249-259] define an algorithm, called FAR, and prove that it is within a logarithmic factor of the optimal online algorithm. We prove that FAR is in fact strongly competitive, i.e., within a constant factor of the optimum. For directed access graphs, we present an algorithm that is strongly competitive on structured program, graphs-graphs that model a subset of the request sequences of structured programs. [References: 13]