Analyzing Replacement Policies In List-based Caches With Non-uniform Access Costs

Authors:
Giuliano Casale Imperial College London, United Kingdom (Great Britain)

Abstract:

List-based caches can offer lower miss rates than single-list caches, but their analysis is challenging due to state-space explosion. We analyze in this setting randomized replacement policies for caches with non-uniform access costs. In our model, costs can depend on the stream a request originated from, the target item, and the list that contains it. We first show that, similarly to the uniform-cost case, the random replacement (RR) and first-in first-out (FIFO) policies can be exactly analyzed using a product-form expression for the equilibrium state probabilities of the cache. We then tackle the state space explosion by means of the singular perturbation method, deriving limiting expressions for the equilibrium performance measures as the number of items and the cache capacity grow in a fixed ratio. Simulations indicate that our asymptotic formulas rapidly converge to the cache equilibrium distribution.

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