Abstract
Constructing deliberative real-time AI systems is challenging due to the high execution-time variance in AI algorithms and the requirement of worst-case bounds for hard real-time guarantees, often resulting in poor use of system resources. Using a motivating case study, the general problem of resource usage maximization is addressed. We approach the issues by employing a hybrid task model for anytime algorithms, which is supported by recent advances in fixed priority scheduling for imprecise computation. In particular, with a novel scheduling scheme based on Dual Priority Scheduling, hard tasks are guaranteed by schedulability analysis and scheduled in favor of optional and anytime components which are executed whenever possible for enhancing system utility. Simulation studies show satisfactory performance on the case study with the application of the scheduling scheme. We also suggest how aperiodic tasks can be scheduled effectively within the framework and how tasks can be prioritized based on their utilities by an efficient algorithm. These works form a comprehensive package of scheduling model, analysis, and algorithms based on fixed priority scheduling, providing a versatile platform where real-time AI applications can be suitably facilitated.
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References
Audsley NC (1991) Optimal priority assignment and feasibility of static priority tasks with arbitrary start times. Technical Report YCS-164, Department of Computer Science, University of York, UK, 1991
Audsley NC, Burns A, Richardson MF, Wellings AJ (1991) Hard real-time scheduling: the deadline monotonic approach. In: Proceedings 8th IEEE workshop on real-time operating systems and software, Atalanta, 1991
Audsley NC, Burns A, Richardson MF, Tindell K (1993a) Applying new scheduling theory to static priority pre-emptive scheduling. Softw Eng J 8(5):284–292
Audsley NC, Burns A, Richardson MF, Wellings AJ (1993b) Incorporating unbounded algorithms into predictable real-time systems. Comput Syst Sci Eng 8(2):80–89
Audsley NC, Burns A, Davis RI, Wellings AJ (1995) Integrating unbounded software components into hard real-time systems. In: Natarajan S (ed) Imprecise and approximate computation. Kluwer Academic, Dordrecht
Bernat G, Burns A (1997) Combining (n/m)-hard deadlines and dual priority scheduling. In: IEEE real-time systems symposium, pp 46–57
Bernat G, Burns A (2002) Multiple servers and capacity sharing for implementing flexible scheduling. Real-Time Syst 22(1–2):49–75
Bernat G, Burns A, Llamosí A (2001) Weakly-hard real-time systems. IEEE Trans Comput 50(4):308–321
Burns A (1994) Preemptive priority based scheduling: an appropriate engineering approach. In: Son S (ed) Advances in real-time systems. Prentice-Hall, Englewood Cliffs, pp 225–248
Burns A, Wellings AJ (2001) Real-time systems and programming languages: Ada 95, real-time Java and real-time POSIX, 3rd edn. Addison-Wesley, Reading
Cheny, Foroughi E, Heintz F, Huangy Z, Kapetanakis S, Kostiadis K, Kummeneje J, Noda I, Obst O, Riley P, Steffens T, Wangy Y, Yiny X (2002) Robocup soccer simulator manual 2002. http://sserver.sf.net/docs/manual.pdf
Chu Y (2007) A tractable schedulability test for imprecise computation. Technical Report YCS-2006-414, Department of Computer Science, University of York, UK
Chu Y, Burns A (2007) Optimal priority ordering for imprecise computation—a utility-based approach. Technical Report YCS-2007-424, Department of Computer Science, University of York, UK
Chung J-Y, Liu JWS, Lin K-J (1990) Scheduling periodic jobs that allow imprecise results. IEEE Trans Comput 39(9):1156–1174
Davis RI, Wellings AJ (1995) Dual priority scheduling. In: IEEE proceedings real-time systems symposium, Pisa, Italy, 1995, pp 100–109
Dean T, Boddy M (1988) An analysis of time-dependent planning. In: Proceedings of the seventh national conference on artificial intelligence, Minneapolis, Minnesota, USA, 1988, pp 49–54
Feng W-C, Liu JWS (1997) Algorithms for scheduling real-time tasks with input error and end-to-end deadlines. IEEE Trans Softw Eng 23(2):93–106
Horling B, Lesser V, Vincent R, Wagner T (2002) The soft real-time agent control architecture. In: Proceedings of the AAAI/KDD/UAI-2002 joint workshop on real-time decision support and diagnosis systems, July 2002
Joseph M, Pandya PK (1986) Finding response times in a real-time system. Comput J 29(5):390–395
Korf RE (1990) Real-time heuristic search. Artif Intell 42(2–3):189–211
Lehoczky J, Ramos-Thuel S (1992) An optimal algorithm for scheduling soft-aperiodic tasks in fixed-priority preemptive systems. In: IEEE proceedings real-time systems symposium, pp 110–123
Lehoczky J, Sha L, Strosnider J (1987) Enhanced aperiodic responsiveness in hard real-time environments. In: Proceedings real-time systems symposium. IEEE Computer Society, New York, pp 261–270
Leung JY, Whitehead J (1982) On the complexity of fixed-priority scheduling of periodic, real-time tasks. Perform Eval 2(4):237–250
Liu CL, Layland JW (1973) Scheduling algorithms for multiprogramming in a hard-real-time environment. J ACM 20(1):46–61
Liu JWS (2000) Real-time systems. Prentice-Hall PTR, Upper Saddle River
Liu JWS, Lin K-J, Shih W-K, Yu AC-S, Chung J-Y, Zhao W (1991) Algorithms for scheduling imprecise computations. Computer 24(5):58–68
Musliner DJ, Durfee EH, Shin KG (1993) CIRCA: a cooperative intelligent real time control architecture. IEEE Trans Syst, Man, Cybern 23(6):1561–1574
Musliner DJ, Hendler JA, Agrawala AK, Durfee EH, Strosnider JK, Paul CJ (1995) The challenges of real-time AI. Computer 28(1):58–66
Russell SJ, Norvig P (2002) Artificial intelligence: a modern approach, 2nd edn. Prentice-Hall, Upper Saddle River
Sha L, Rajkumar R, Lehoczky JP (1990) Priority inheritance protocols: an approach to real-time synchronization. IEEE Trans Comput 39(9):1175–1185
Stankovic JA, Rajkumar R (2004) Real-time operating systems. Real-Time Syst 28(2–3):237–253
Strosnider J, Lehoczky J, Sha L (1995) The deferrable server algorithm for enhanced aperiodic responsiveness in hard real-time environments. IEEE Trans Comput 44(1):73–91
Tindell K (1992) Using offset information to analyse static priority pre-emptively scheduled task sets. Technical Report YCS-92-182, Department of Computer Science, University of York, UK
Zilberstein S (1993) Operational rationality through compilation of anytime algorithms. PhD thesis, University of California at Berkeley
Zilberstein S, Russell S (1995) Approximate reasoning using anytime algorithms. In: Natarajan S (ed) Imprecise and approximate computation. Kluwer Academic, Dordrecht
Zilberstein S, Russell S (1996) Optimal composition of real-time systems. Artif Intell 82(1–2):181–213
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Chu, Y., Burns, A. Flexible hard real-time scheduling for deliberative AI systems. Real-Time Syst 40, 241–263 (2008). https://doi.org/10.1007/s11241-008-9058-1
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DOI: https://doi.org/10.1007/s11241-008-9058-1