Advertisement

Real-Time Systems

, Volume 40, Issue 2, pp 208–237 | Cite as

On earliest deadline first scheduling for temporal consistency maintenance

  • Ming Xiong
  • Qiong Wang
  • Krithi Ramamritham
Article

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.

Keywords

Real-time databases Temporal consistency Earliest deadline first 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Baruah SK, Mok AK, Rosier LE (1990a) Preemptively scheduling hard-real-time sporadic tasks on one processor. IEEE Real-Time Syst Symp, December1990 Google Scholar
  2. 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 CrossRefGoogle Scholar
  3. Burns A, Davis R (1996) Choosing task periods to minimise system utilisation in time triggered systems. Inf Process Lett 58:223–229 zbMATHCrossRefGoogle Scholar
  4. Gerber R, Hong S, Saksena M (1994) Guaranteeing end-to-end timing constraints by calibrating intermediate processes. IEEE Real-Time Syst Symp, December 1994 Google Scholar
  5. 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 Google Scholar
  6. Gustafsson T, Hansson J (2004b) Dynamic on-demand updating of data in real-time database systems. In: ACM SAC 2004 Google Scholar
  7. Hiller FS, Lieberman GJ (1990) Introduction to operations research. McGraw-Hill, New York Google Scholar
  8. 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 Google Scholar
  9. Kuo T, Mok AK (1992) Real-time data semantics and similarity-based concurrency control. IEEE Real-Time Syst Symp, December 1992 Google Scholar
  10. Kuo T, Mok AK (1993) SSP: a semantics-based protocol for real-time data access. IEEE Real-Time Syst Symp, December 1993 Google Scholar
  11. Ho S, Kuo T, Mok AK (1997) Similarity-based load adjustment for static real-time transaction systems. IEEE Real-Time Syst Symp Google Scholar
  12. Lehoczky JP (1990) Fixed priority scheduling of periodic task sets with arbitrary deadlines. IEEE Real-Time Syst Symp Google Scholar
  13. Liu CL, Layland J (1973) Scheduling algorithms for multiprogramming in a hard real-time environment. J Assoc Comput Mach 20(1):46–61 zbMATHMathSciNetGoogle Scholar
  14. Leung J, Whitehead J (1982) On the complexity of fixed-priority scheduling of periodic real-time tasks. Perform Eval 2:237–250 zbMATHCrossRefMathSciNetGoogle Scholar
  15. Ramamritham K (1993) Real-time databases. Distributed and Parallel Databases 1(1993):199–226 CrossRefGoogle Scholar
  16. Ripoll I, Crespo A, Mok A (1996) Improvement in feasibility testing for real-time tasks. Real-Time Syst 11(1):19–39 CrossRefGoogle Scholar
  17. Seto D, Lehoczky JP, Sha L, Shin KG (1996) On task schedulability in real-time control systems. IEEE Real-Time Syst Symp, December 1996 Google Scholar
  18. Seto D, Lehoczky JP, Sha L (1998) Task period selection and schedulability in real-time systems. IEEE Real-Time Syst Symp, December 1998 Google Scholar
  19. Song X, Liu JWS (1995) Maintaining temporal consistency: pessimistic vs. optimistic concurrency control. IEEE Trans Knowl Data Eng 7(5):786–796 CrossRefGoogle Scholar
  20. Stankovic JA, Spuri M, Ramamritham K, Buttazzo GC (1998) Deadline scheduling for real-time systems: EDF and related algorithms. Kluwer Academic, Dordrecht Google Scholar
  21. Wolsey LA (1998) Integer programming. Wiley, New York zbMATHGoogle Scholar
  22. Xiong M, Ramamritham K (1999) Deriving deadlines and periods for real-time update transactions. IEEE Real-Time Syst Symp Google Scholar
  23. 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 CrossRefGoogle Scholar
  24. Xiong M, Han S, Lam KY (2005) A deferrable scheduling algorithm for real-time transactions maintaining data freshness. IEEE Real-Time Syst Symp Google Scholar
  25. 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 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Bell LaboratoriesAlcatel-LucentMurray HillUSA
  2. 2.India Institute of Technology BombayPowaiIndia

Personalised recommendations