An Analysis of EDF Schedulability on a Multiprocessor

  • Authors:
  • Theodore P. Baker

  • Affiliations:
  • IEEE

  • Venue:
  • IEEE Transactions on Parallel and Distributed Systems
  • Year:
  • 2005

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Abstract

A new schedulability test is derived for preemptive deadline scheduling of periodic or sporadic real-time tasks on a single-queue m-server system. The new test allows the task deadline to be more or less than the task period, and is based on a new analysis concept, called a \mu{\hbox{-}}{\rm{busy}} interval. This generalizes a result of Goossens et al. [11] that a system of periodic tasks with maximum individual task utilization u_{max} is EDF-schedulable on m processors if the total utilization does not exceed m(1-u_{max})+u_{max}. The new test allows the analysis of hybrid EDF-US [x] scheduling, and the conclusion that EDF-US[1/2] is optimal, with a guaranteed worst-case schedulable utilization of (m+1)/2.