Abstract
While scheduling theory has been developed over a long period of time, it is important to note that most results concern problems with static characteristics. However, a real-time system is dynamic and requires on-line and adaptive scheduling strategies. So, an important aspect of real-time systems research is to devise methods flexible enough to react to a dynamic change of processor load and to attempt to schedule all the tasks judiciously.
In this paper, we are particularly concerned with the problem of scheduling tasks which are of two kinds: periodic and sporadic, on a monoprocessor machine. Periodic tasks are independent, run cyclically and their characteristics are known in advance. In addition, we allow for the unpredictable occurrence of aperiodic task groups, with timing and precedence constraints. Clearly, the main problem is to devise a schedulability test that makes it possible to decide whether a new occurring group can be accepted, without upsetting the tight timing behavior requirements.
We present an optimal acceptance test which returns a decision on the basis of the current state of processor load and by considering tasks to be scheduled according to the well known preemptive algorithm Earliest Deadline. The acceptance algorithm and a complexity analysis are presented.
Similar content being viewed by others
References
Blazewicz, J. 1976. Scheduling dependent tasks with different arrival times to meet deadlines. In E.Gelenbe, H.Beilner (eds), Modelling and Performance Evaluation of Computer Systems, Amsterdam, North-Holland, 1976 pp 57–65.
Blazewicz, J., Cellary, W., Slowinsky, R., and Weglarz, J. 1986. Scheduling under resource constraints — Deterministic models. In P.L.Hammer (eds), Annals of Operations Research, Vol 7. Basel, J.C. Baltzer AG.
Cheng, S., Stankovic, J.A., and Ramamritham, K. 1986. Dynamic scheduling of groups of tasks with precedence constraints in distributed hard real time systems. In Proc. Real-time Systems Symposium, (Feb.), Louisiana, pp 285–298.
Chetto, H., and Chetto, M. 1987. How to insure feasibility in distributed system for real-time control. International Symposium on High Performance Computer Systems, Paris, (Dec.).
Chetto, H., and Chetto, M. 1989. Some results of the earliest deadline scheduling algorithm. IEEE Transactions on Software Engineering, 15, (10) (Oct.): 1261, 1269.
Chetto, H. and Chetto, M. 1989. Scheduling periodic and sporadic tasks in a real time system. Info. Proc. Letters, 30, (4):177–184.
Garey, M.R. and Johnson, D.S. 1977. Two-processor scheduling with start times and deadlines. SIAM J. on Computing, 6:416–426.
Garey, M.R. and Johnson, D.S. 1979. Computer and Intractability: A Guide to the Theory of NP-completeness. San Francisco: Freeman.
Henn, R. 1978. Antwortzeitgesteuerte Prozessorzuteilung unter Strengen Zeitbedingungen. 1978. Computing (19):202–220.
Labetoulle, J. 1974. Some theorems on real-time scheduling. In E.Gelenbe and R.Mahl (eds) Computer Architecture and Networks, Amsterdam, North-Holland, pp 285–298.
Lawler, E.L. and Moors, J.M. 1969. A functional equation and its application to resource allocation and scheduling problems. Management science, 16 (1):77–84.
Lenstra, J.K., Rinnooykan, A.H.G., and Brucker, P. 1977. Complexity of machine scheduling problems. Ann. Discrete Math. 1:343–362.
Leung, J.Y.T., and Merril, M.L. 1980. A note on preemptive scheduling of periodic real-time tasks. Info. Proc. Letters, 11, (3): 115–118.
Liu, C.L. and Layland, J.W. 1973. Scheduling algorithms for multiprogramming in a hard real-time environment. JACM, 20, (1):46–61.
Ramamritham, K., and Stankovic, J.A. 1984. Dynamic task scheduling in distributed hard real-time systems. IEEE Software, (July):65–75.
Serlin, O. 1972. Scheduling of time critical processes. In Proceedings of the Spring Joint Computers Conference, 40:925–932.
Sorenson, P.G. 1974. A methodology for real-time system development. P.H.D. University of Toronto, Canada 1974.
Stankovic, J.A. 1988. A serious problem for next-generation systems. IEEE Computer 21, (10):10–19.
Zhao, W. and Ramamritham, K. 1985. Distributed scheduling using bidding and focussed addressing. In Proc. Real-Time Syst. Symposium, San Diego, (Dec. 3–6):103–111.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chetto, H., Silly, M. & Bouchentouf, T. Dynamic scheduling of real-time tasks under precedence constraints. The Journal of Real-Time Systems 2, 181–194 (1990). https://doi.org/10.1007/BF00365326
Issue Date:
DOI: https://doi.org/10.1007/BF00365326