Some Guidelines for Proportional Share CPU Scheduling in General-Purpose Operating Systems

John Regehr

University of Utah, School of Computing
50 South Central Campus Drive, Room 3190
Salt Lake City, Utah 84112-9205


Our premise is that since there already exists a large, mature body of literature on real-time scheduling in general-purpose operating systems, it is time to spend more effort deciding which of these algorithms should be used and when, and less effort on generating new algorithms. In this paper we focus on proportional share schedulers. We introduce the notion of pessimism -- the proportion of over-reservation required for an application to meet real-time deadlines when scheduled by proportional share schedulers that have bounded allocation error. We study the implications of pessimism and its effect on the selection of scheduling algorithm and scheduling quantum size, and also the interaction of quantum size and context switch overhead. Finally, we examine the implications of these tradeoffs for the design of applications and schedulers.

Presented as a work in progress at the 22nd IEEE Real-Time Systems Symposium (RTSS 2001), London, UK, December 3-6 2001.

Copyright 2001 IEEE.

Citation information:

  author =       "John Regehr",
  title =        "Some Guidelines for Proportional Share {CPU} Scheduling in
                  General-Purpose Operating Systems",
  booktitle =    "Work in progress session of the 22nd IEEE Real-Time Systems
                 Symposium (RTSS 2001)",
  address =      "London, UK",
  month =        dec,
  year =         "2001",

John Regehr <>
Last modified: Fri May 31 10:45:28 MDT 2002