Properties of the working-set model

  • Authors:
  • Peter J. Denning;Stuart C. Schwartz

  • Affiliations:
  • Princeton Univ., Princeton, NJ;Princeton Univ., Princeton, NJ

  • Venue:
  • Communications of the ACM
  • Year:
  • 1972

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Abstract

A program's working set W(t, T) at time t is the set of distinct pages among the T most recently referenced pages. Relations between the average working-set size, the missing-page rate, and the interreference-interval distribution may be derived both from time-average definitions and from ensemble-average (statistical) definitions. An efficient algorithm for estimating these quantities is given. The relation to LRU (lease recently used) paging is characterized. The independent-reference model, in which page references are statistically independent, is used to assess the effects of interpage dependencies on working-set size observations. Under general assumptions, working-set size is shown to be normally distributed.