Statistical Properties of the Buddy System

  • Authors:
  • Paul W. Purdom, Jr.;Stephen M. Stigler

  • Affiliations:
  • Bell Telephone Laboratories, Naperville, Ill and University of Wisconsin, Computer Science Department and Statistics Department, Madison, Wisconsin;University of Wisconsin, Computer Science Department and Statistics Department, Madison, Wisconsin

  • Venue:
  • Journal of the ACM (JACM)
  • Year:
  • 1970

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Abstract

The utilization of space and the running speed of the buddy system are considered Equations are derived that give various statistical properties of the buddy system. For the bottom level with Poisson requests and exponential service times the expected amount of space wasted by pairing full cells with empty cells is about 0.513 &rgr;1/2 and the mean time between requests from the bottom level to the next level is about 1.880 &rgr;1/2 &lgr;-1, where &rgr; is the mean number of blocks in use on the bottom level and &lgr;-1 is the mean time between requests for blocks on the bottom level. The results of a number of simulations of the buddy system are also given and compared with the analytical studies.