Optimizing TTL Caches under Heavy-Tailed Demands

Abstract

In this paper we analyze the hit performance of cache systems that receive file requests with general arrival distributions and different popularities. We consider timer-based (TTL) policies, with differentiated timers over which we optimize. The optimal policy is shown to be related to the monotonicity of the hazard rate function of the inter-arrival distribution. In particular for decreasing hazard rates, timer policies outperform the static policy of caching the most popular contents. We provide explicit solutions for the optimal policy in the case of Pareto-distributed inter-request times and a Zipf distribution of file popularities, including a compact fluid characterization in the limit of a large number of files. We compare it through simulation with classical policies, such as least-recently-used and discuss its performance. Finally, we analyze extensions of the optimization framework to a line network of caches.

Document Details

Document Type
Pub Defense Publication
Publication Date
Jun 14, 2016
Source ID
10.1145/2964791.2901459

Entities

People

  • AndrĂ©s Ferragut
  • Fernando Paganini
  • Ismael Rodriguez

Organizations

  • Air Force Office of Scientific Research
  • Universidad ORT Uruguay

Tags

Fields of Study

  • Computer science

Readers

  • Mathematical Modeling and Probability Theory.
  • Parallel and Distributed Computing.
  • Theoretical Analysis.