Abstract
A real-time object is one whose state may become invalid with the passage of time. A temporal validity interval is associated with the object state, and the real-time object is temporally consistent if its temporal validity interval has not expired. Clearly, the problem of maintaining temporal consistency of data is motivated by the need for a real-time system to track its environment correctly. Hence, sensor transactions must be able to execute periodically and also each instance of a transaction should perform the relevant data update before its deadline.
Unfortunately, the period and deadline assignment problem for periodic sensor transactions has not received the attention that it deserves. An exception is the More-Less scheme, which uses the Deadline Monotonic (DM) algorithm for scheduling periodic sensor transactions. However, there is no work addressing this problem from the perspective of dynamic priority scheduling. In this paper, we examine the problem of temporal consistency maintenance using the Earliest Deadline First (EDF) algorithm in three steps:
First, the problem is transformed to another problem with a sufficient (but not necessary) condition for feasibly assigning periods and deadlines. An optimal solution for the problem can be found in linear time, and the resulting processor utilization is characterized and compared to a traditional approach. Second, an algorithm to search for the optimal periods and deadlines is proposed. The problem can be solved for sensor transactions that require any arbitrary deadlines. However, the optimal algorithm does not scale well when the problem size increases. Hence, thirdly, we propose a heuristic search-based algorithm that is more efficient than the optimal algorithm and is capable of finding a solution if one exists.
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References
Baruah SK, Mok AK, Rosier LE (1990a) Preemptively scheduling hard-real-time sporadic tasks on one processor. IEEE Real-Time Syst Symp, December1990
Baruah SK, Howell RR, Rosier LE (1990b) Algorithms and complexity concerning the preemptive scheduling of periodic, real-time tasks on one processor. Real-Time Syst 2(4):301–324
Burns A, Davis R (1996) Choosing task periods to minimise system utilisation in time triggered systems. Inf Process Lett 58:223–229
Gerber R, Hong S, Saksena M (1994) Guaranteeing end-to-end timing constraints by calibrating intermediate processes. IEEE Real-Time Syst Symp, December 1994
Gustafsson T, Hansson J (2004a) Data management in real-time systems: a case of on-demand updates in vehicle control systems. In: IEEE real-time and embedded technology and applications symposium, pp 182–191
Gustafsson T, Hansson J (2004b) Dynamic on-demand updating of data in real-time database systems. In: ACM SAC 2004
Hiller FS, Lieberman GJ (1990) Introduction to operations research. McGraw-Hill, New York
Kang KD, Son S, Stankovic JA, Abdelzaher T (2002) A QoS-sensitive approach for timeliness and freshness guarantees in real-time databases. In: EuroMicro real-time systems conference, June 2002
Kuo T, Mok AK (1992) Real-time data semantics and similarity-based concurrency control. IEEE Real-Time Syst Symp, December 1992
Kuo T, Mok AK (1993) SSP: a semantics-based protocol for real-time data access. IEEE Real-Time Syst Symp, December 1993
Ho S, Kuo T, Mok AK (1997) Similarity-based load adjustment for static real-time transaction systems. IEEE Real-Time Syst Symp
Lehoczky JP (1990) Fixed priority scheduling of periodic task sets with arbitrary deadlines. IEEE Real-Time Syst Symp
Liu CL, Layland J (1973) Scheduling algorithms for multiprogramming in a hard real-time environment. J Assoc Comput Mach 20(1):46–61
Leung J, Whitehead J (1982) On the complexity of fixed-priority scheduling of periodic real-time tasks. Perform Eval 2:237–250
Ramamritham K (1993) Real-time databases. Distributed and Parallel Databases 1(1993):199–226
Ripoll I, Crespo A, Mok A (1996) Improvement in feasibility testing for real-time tasks. Real-Time Syst 11(1):19–39
Seto D, Lehoczky JP, Sha L, Shin KG (1996) On task schedulability in real-time control systems. IEEE Real-Time Syst Symp, December 1996
Seto D, Lehoczky JP, Sha L (1998) Task period selection and schedulability in real-time systems. IEEE Real-Time Syst Symp, December 1998
Song X, Liu JWS (1995) Maintaining temporal consistency: pessimistic vs. optimistic concurrency control. IEEE Trans Knowl Data Eng 7(5):786–796
Stankovic JA, Spuri M, Ramamritham K, Buttazzo GC (1998) Deadline scheduling for real-time systems: EDF and related algorithms. Kluwer Academic, Dordrecht
Wolsey LA (1998) Integer programming. Wiley, New York
Xiong M, Ramamritham K (1999) Deriving deadlines and periods for real-time update transactions. IEEE Real-Time Syst Symp
Xiong M, Ramamritham K, Stankovic J, Towsley D, Sivasankaran RM (2002) Scheduling transactions with temporal constraints: exploiting data semantics. IEEE Trans Knowl Data Eng 14(5):1155–1166
Xiong M, Han S, Lam KY (2005) A deferrable scheduling algorithm for real-time transactions maintaining data freshness. IEEE Real-Time Syst Symp
Xiong M, Liang B, Lam K, Guo Y (2006) Quality of service guarantee for temporal consistency of real-time transactions. IEEE Trans Knowl Data Eng 18(8):1097–1110
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Xiong, M., Wang, Q. & Ramamritham, K. On earliest deadline first scheduling for temporal consistency maintenance. Real-Time Syst 40, 208–237 (2008). https://doi.org/10.1007/s11241-008-9055-4
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DOI: https://doi.org/10.1007/s11241-008-9055-4