Real-Time Systems

, Volume 11, Issue 1, pp 19–39 | Cite as

Improvement in feasibility testing for real-time tasks

  • Ismael Ripoll
  • Alfons Crespo
  • Aloysius K. Mok


Scheduling analysis in real-time systems require an off-line feasibility (schedulability) test to guarantee the response time of critical tasks. There are fast and efficient tests for static schedulers. However, when a dynamic scheduler is required, the available tests are not as feast and efficient as static ones. In this paper, two different characterizations of feasible task sets are presented. These characterizations lead to an new feasibility algorithm. The proposed algorithm has an worst-case exponential complexity, but experimental results indicated that it runs on pseudo-polynomial time for a very large percentage of task sets. The algorithm also provides a sufficient condition for feasible asynchronous task sets. One of the main contributions of this work is the theoretical approach used to obtain the new feasibility test. The results of a large number of simulations, as well as, the theoretical demonstrations point out the improvements reached over previous tests.


Operating System Theoretical Approach Computing Methodology Previous Test Critical Task 
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  1. AudsleyN. C., BurnsA., DavidR. I., TindellK. W. and WellingsA. J. “Fixed Priority Pre-emptive Scheduling: An Historical Prespective”, Real-Time Systems, Vol 8(2/3), Mar/May 1995, pp. 173–198.Google Scholar
  2. AudsleyN. C., BurnsA., RichardsonM., TindellK.W. and WellingsA. J. “Applying New Scheduling Theory to Static Priority Pre-emptive Scheduling”, Software Engineering Journal, Vol. 8(5) Sept 1993 pp. 284–292.Google Scholar
  3. Baruah, S., Mok, A., and Rosier, L. “Preemptively Scheduling Hard-Real-Time Sporadic Tasks on One periodic”, 11th Real-Time Systems Symposium, Dec 1990, pp. 182–190.Google Scholar
  4. Baruah, S., Rosier, L. and Howell, R. R. “Algorithms and Complexity Concerning the Preemptive Scheduling of Periodic, Real-Time Tasks on One Processor”, Real-Time Systems, Dec 1990, pp. 301–324.Google Scholar
  5. Bihari, T., and Schwan, K. “Dynamic adaptation of Real-Time software”, ACM Trans. Computer Syst. and Software, May 1991.Google Scholar
  6. Burns, A., Wellings, A. J., Bailey, C. M. and Fyfe, E. “The Olympus Attitude and Orbital Control System: A Case Study in Hard Real-Time System Design and Implementation”, Department of Computer Science, University of York, report YCS 190 1993.Google Scholar
  7. Chetto, H. and Chetto, M. “Some results of the Earliest Deadline Scheduling Algorithm”, IEEE Transactions Software Engineering, Oct 1989.Google Scholar
  8. Dertouzos, M. “Control robotics: the procedural control of physical processors”, Proceedings of the IFIP Congress, 1974, pp. 807–813.Google Scholar
  9. Garey, M. R., and Johnson, D. S. “Computer And Intractability, A Guide to the Theory of NP-Completeness”, Ed: W. H. Freeman And Company, 1979.Google Scholar
  10. KnuthD. “The art of computer programming”, Vol. 2, 1969, pp. 293–304.Google Scholar
  11. LiuC. and LaylandJ. “Scheduling algorithms for multiprogramming in a hard Real-Time environment”, Journal of the ACM, Vol. 20(1) 1973, pp. 46–61.Google Scholar
  12. Lehoczky, J. P. “Fixed priority scheduling of periodic task sets with arbitrary deadlines”, Proceedings of the 11th IEEE Real-Time Systems Symposium, Dec 1990, pp. 201–209.Google Scholar
  13. LeungJ. and MerrillM. “A note on the preemptive scheduling of periodic, Real-Time tasks” Information Processing Letters, Vol. 11, 1980, pp. 115–118.Google Scholar
  14. LeungJ. and WhiteheadJ. “On the complexity of fixed-priority scheduling of periodic, Real-Time tasks”, Performance Evaluation, Vol. 2(4), Dec 1982, pp. 237–250.Google Scholar
  15. Mok, A. “Fundamental Design Problems of Distributed Systems for the Hard Real-Time Environment”, PhD Thesis, MIT Laboratory for Computer Science, May 1983.Google Scholar
  16. SRL90 ShaL., RajkumarR. and LehoczkyJ. P. “Priority inheritance protocols: An approach to real-time synchronization”, IEEE Transactions on Computers, Vol. 93, Sep 1990, pp. 1175–1185.Google Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Ismael Ripoll
    • 1
  • Alfons Crespo
    • 1
  • Aloysius K. Mok
    • 2
  1. 1.Dpto. de Ingenieria de Sistemas, Computadores y AutomáticaUniversidad Politécnica de ValenciaSpain
  2. 2.Department of Computer SciencesThe University of Texas at AustinUSA

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