Real-Time Systems

, Volume 47, Issue 1, pp 1–40 | Cite as

Improved priority assignment for global fixed priority pre-emptive scheduling in multiprocessor real-time systems

  • Robert I. DavisEmail author
  • Alan Burns


This paper is an extended version of a paper that appeared in the proceedings of the IEEE Real-Time Systems Symposium 2009. This paper has been updated with respect to advances made in schedulability analysis, and contains a number of significant additional results.

The paper addresses the problem of priority assignment in multiprocessor real-time systems using global fixed task-priority pre-emptive scheduling.

We prove that Audsley’s Optimal Priority Assignment (OPA) algorithm, originally devised for uniprocessor scheduling, is applicable to the multiprocessor case, provided that three conditions hold with respect to the schedulability tests used. Our empirical investigations show that the combination of optimal priority assignment policy and a simple compatible schedulability test is highly effective in terms of the number of tasksets deemed to be schedulable.

We also examine the performance of heuristic priority assignment policies such as Deadline Monotonic, and an extension of the TkC priority assignment policy called DkC that can be used with any schedulability test. Here we find that Deadline Monotonic priority assignment has relatively poor performance in the multiprocessor case, while DkC priority assignment is highly effective.


Real-time Multiprocessor Multicore Optimal priority assignment Heuristic priority assignment Global scheduling Fixed priority Taskset generation Schedulability analysis 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Andersson B (2008) Global static-priority preemptive multiprocessor scheduling with utilization bound 38%. In: Proc international conference on principles of distributed systems, pp 73–88 Google Scholar
  2. Andersson B, Jonsson J (2000a) Some insights on fixed-priority pre-emptive non-partitioned multiprocessor scheduling. In: Proc RTSS—work-in-progress session Google Scholar
  3. Andersson B, Jonsson J (2000b) Fixed-priority preemptive multiprocessor scheduling: to partition or not to partition. In: Proc RTCSA Google Scholar
  4. Andersson B, Jonsson J (2003) The utilization bounds of partitioned and pfair static-priority scheduling on multiprocessors are 50%. In: Proc ECRTS, pp 33–40 Google Scholar
  5. Andersson B, Baruah SK, Jonsson J (2001) Static-priority scheduling on multiprocessors. In: Proc RTSS, pp 193–202 Google Scholar
  6. Audsley NC (1991) Optimal priority assignment and feasibility of static priority tasks with arbitrary start times. Technical report YCS 164, Dept Computer Science, University of York, UK Google Scholar
  7. Audsley NC (2001) On priority assignment in fixed priority scheduling. Inf Process Lett 79(1):39–44 zbMATHCrossRefGoogle Scholar
  8. Baker TP (2003) Multiprocessor EDF and deadline monotonic schedulability analysis. In: Proc RTSS, pp 120–129 Google Scholar
  9. Baker TP (2005) An analysis of EDF scheduling on a multiprocessor. IEEE Trans Parallel Distrib Syst 15(8):760–768 CrossRefGoogle Scholar
  10. Baker TP (2006) An analysis of fixed-priority scheduling on a multiprocessor. Real-Time Syst 32(1–2):49–71 zbMATHCrossRefGoogle Scholar
  11. Baker TP, Baruah SK (2009) Sustainable multiprocessor scheduling of sporadic task systems. In: Proc ECRTS, pp 141–150 Google Scholar
  12. Baker TP, Cirinei M, Bertogna M (2008) EDZL scheduling analysis. Real-Time Syst 40(3):264–289 zbMATHCrossRefGoogle Scholar
  13. Baruah SK (2007) Techniques for multiprocessor global schedulability analysis. In: Proc RTSS, pp 119–128 Google Scholar
  14. Baruah SK (2009) Schedulability analysis of global deadline monotonic scheduling. Technical report, available from
  15. Baruah SK, Baker TP (2009) An analysis of global EDF schedulability for arbitrary sporadic task systems. Real-Time Syst 43(1):3–24. ECRTS special issue zbMATHCrossRefGoogle Scholar
  16. Baruah SK, Fisher N (2008) Global fixed-priority scheduling of arbitrary-deadline sporadic task systems. In: Proc of the 9th int’l conference on distributed computing and networking, pp 215–226 Google Scholar
  17. Baruah SK, Bonifaci V, Marchetti-Spaccamela A, Stiller S (2009) Implementation of a speedup-optimal global EDF schedulability test. In: Proc ECRTS, pp 259–268 Google Scholar
  18. Bertogna M (2007) Real-time scheduling for multiprocessor platforms. PhD Thesis, Scuola Superiore Sant’Anna, Pisa Google Scholar
  19. Bertogna M (2009) Evaluation of existing schedulability tests for global EDF. In: Proceedings of the first international workshop on real-time systems on multicore platforms: theory and practice Google Scholar
  20. Bertogna M, Cirinei M (2007) Response time analysis for global scheduled symmetric multiprocessor platforms. In: Proc RTSS, pp 149–158 Google Scholar
  21. Bertogna M, Cirinei M, Lipari G (2005) New schedulability tests for real-time task sets scheduled by deadline monotonic on multiprocessors. In: Proc 9th international conf on principles of distributed systems, pp 306–321 Google Scholar
  22. Bertogna M, Cirinei M, Lipari G (2009) Schedulability analysis of global scheduling algorithms on multiprocessor platforms. IEEE Trans Parallel Distrib Syst 20(4):553–566 CrossRefGoogle Scholar
  23. Bini E, Buttazzo GC (2005) Measuring the performance of schedulability tests. Real-Time Syst 30(1–2):129–154 zbMATHCrossRefGoogle Scholar
  24. Cirinei M, Baker TP (2007) EDZL scheduling analysis. In: Proc ECRTS, pp 9–18 Google Scholar
  25. Cucu L (2008) Optimal priority assignment for periodic tasks on unrelated processors. In: Proc ECRTS WiP session Google Scholar
  26. Cucu L, Goossens J (2006) Feasibility intervals for fixed-priority real-time scheduling on uniform multiprocessors. In: Proc 11th IEEE international conference on emerging technologies and factory automation Google Scholar
  27. Cucu L, Goossens J (2007) Feasibility intervals for multiprocessor fixed-priority scheduling of arbitrary deadline periodic systems. In: Proc DATE, pp 1635–1640 Google Scholar
  28. Davis RI, Burns A (2007) Robust priority assignment for fixed priority real-time systems. In: Proc RTSS, pp 3–14 Google Scholar
  29. Davis RI, Burns A (2009a) Priority assignment for global fixed priority pre-emptive scheduling in multiprocessor real-time systems. In: Proc RTSS, pp 398–409 Google Scholar
  30. Davis RI, Burns A (2009b) A survey of hard real-time scheduling algorithms and schedulability analysis techniques for multiprocessor systems. Available from (to appear in ACM Comput Surv)
  31. Davis RI, Burns A (2010) On optimal priority assignment for response time analysis of global fixed priority pre-emptive scheduling in multiprocessor hard real-time systems. Technical report YCS-2010-451, Department of Computer Science, University of York, Google Scholar
  32. Dhall SK, Liu CL (1978) On a real-time scheduling problem. Oper Res 26(1):127–140 zbMATHCrossRefMathSciNetGoogle Scholar
  33. Easwaran A, Shin I, Lee I (2008) Toward optimal mutiprocessor scheduling for arbitrary deadline tasks. In: Proc RTSS WiP, pp 1–4 Google Scholar
  34. Fisher N, Baruah SK (2006) Global static-priority scheduling of sporadic task systems on multiprocessor platforms. In: Proc IASTED international conference on parallel and distributed computing and systems Google Scholar
  35. Goossens J, Funk S, Baruah SK (2003) Priority-driven scheduling of periodic task systems on multiprocessors. Real-Time Syst 25(2–3):187–205 zbMATHCrossRefGoogle Scholar
  36. Guan N, Stigge M, Yi W, Yu G (2009) New response time bounds for fixed priority multiprocessor scheduling. In: Proceedings of the real-time systems symposium, pp 388–397 Google Scholar
  37. Lauzac S, Melhem R, Mosse D (1998) Comparison of global and partitioning schemes for scheduling rate monotonic tasks on a multiprocessor. In: Proc of the EuroMicro workshop on real-time systems, pp 188–195 Google Scholar
  38. Leteinturier P (2007) Multi-core processors: driving the evolution of automotive electronics architectures. In: 16/09/2007 Google Scholar
  39. Leung JY-T, Whitehead J (1982) On the complexity of fixed-priority scheduling of periodic real-time tasks. Perform Eval 2(4):237–250 zbMATHCrossRefMathSciNetGoogle Scholar
  40. Liu CL (1969) Scheduling algorithms for multiprocessors in a hard real-time environment. In: JPL space programs summary, vols 37–60, pp 28–31 Google Scholar
  41. Liu CL, Layland JW (1973) Scheduling algorithms for multiprogramming in a hard-real-time environment. J ACM 20(1):46–61 zbMATHCrossRefMathSciNetGoogle Scholar
  42. Lundberg L (2002) Analyzing fixed-priority global multiprocessor scheduling. In: Eighth IEEE real-time and embedded technology and applications symposium Google Scholar
  43. Rosenburg B (2009) Product focus: software. In: Avionics magazine, 1st Oct 2009 Google Scholar
  44. Serlin O (1972) Scheduling of time critical processes. In: Proceedings AFIPS spring computing conference, pp 925–932 Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  1. 1.Real-Time Systems Research Group, Department of Computer ScienceUniversity of YorkYorkUK

Personalised recommendations