Real-Time Systems

, Volume 9, Issue 3, pp 207–239 | Cite as

Allocating fixed-priority periodic tasks on multiprocessor systems

  • Yingfeng Oh
  • Sang H. Son


In this paper, we study the problem of allocating a set of periodic tasks on a multiprocessor system such that tasks are scheduled to meet their deadlines on individual processors by the Rate-Monotonic scheduling algorithm. A new schedulability condition is developed for the Rate-Monotonic scheduling that allows us to develop more efficient on-line allocation algorithms. Two on-line allocation algorithms—RM-FF and RM-BF are presented, and shown that their worst-case performance, over the optimal allocation, is upper bounded by 2.33 and lower bounded by 2.28. Then RM-FF and RM-BF are further improved to form two new algorithms: Refined-RM-FF (RRM-FF) and Refined-RM-BF (RRM-BF), both of which have a worst-case performance bound of 2. We also show that when the maximum allowable utilization of a task is small, the worst-case performance of all the new algorithms can be significantly improved. The worst-case performance bounds of RRM-FF and RRM-BF are currently the best bounds in the class of on-line scheduling algorithms proposed to solve the same scheduling problem. Simulation studies show that the average-case performance of the newly proposed algorithms is significantly superior to those in the existing literature.


System Performance Simulation Study Schedule Problem Schedule Algorithm Performance Bound 
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Copyright information

© Kluwer Academic Publishers 1995

Authors and Affiliations

  • Yingfeng Oh
    • 1
  • Sang H. Son
    • 1
  1. 1.Department of Computer ScienceUniversity of VirginiaCharlottesvilleUSA

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