A Period Assignment Algorithm for Real-Time System Design
Digital controllers found in many industrial real-time systems consist of a number of interacting periodic tasks. To sustain the required control quality, these tasks possess the maximum activation periods as performance constraints. An essential step in developing a real-time system is thus to assign each of these tasks a constant period such that the maximum activation requirements are met while the system utilization is minimized .
Given a task graph design allowing producer/consumer relationships among tasks , resource demands of tasks, and range constraints on periods, the period assignment problem falls into a class of nonlinear optimization problems. This paper proposes a polynomial time approximation algorithm which produces a solution whose utilization does not exceed twice the optimal utilization. Our experimental analysis shows that the proposed algorithm finds solutions which are very close to the optimal ones in most cases of practical interest.
KeywordsTask Graph Nonlinear Optimization Problem Optimal Utilization Task Execution Time Range Constraint
- 1.T. F. Abdelzaher, E. M. Atkins, and K. G. Shin. QoS negotiation in real-time systems and its application to automated flight control. In Proceedings of IEEE Real-Time Technology and Applications, pages 228–238, December 1997.Google Scholar
- 2.V. A. F. Almeida, I. M. Vasconcelos, J. N. C. Arabe, and D. A. Menasce. Using random task graphs to investigate the potential benefits of heterogeneity in parallel systems. In Proceedings of Supercomputing, pages 683–691, 1992.Google Scholar
- 4.K. Jeffay. The real-time producer/consumer paradigm: A paradigm for the construction of Efficient, predictable real-time systems. In ACM/SIGAPP Symposium on Applied Computing, pages 796–804. ACM Press, February 1993.Google Scholar
- 5.J. Lehoczky, L. Sha and Y. Ding. The rate monotonic scheduling algorithm: Exact characterization and average case behavior. In Proceedings of IEEE Real-Time Systems Symposium, pages 166–171, December 1989.Google Scholar
- 7.C. Park and A. Shaw. Experimenting with a program timing tool based on source-level timing schema. In Proceedings of IEEE Real-Time Systems Symposium, pages 72–81, December 1990.Google Scholar
- 8.R. Rajkumar, C. Lee, J. Lehoczky, and D. Siewiorek. A resource allocation model for QoS management. In Proceedings of IEEE Real-Time Systems Symposium, pages 298–307, December 1997.Google Scholar
- 9.D. Seto, J. P. Lehoczky, L. Sha, and K. G. Shin. On task schedulability in real-time control systems. In Proceedings of IEEE Real-Time Systems Symposium, pages 13–21, December 1996.Google Scholar