The Community for Technology Leaders
RSS Icon
Issue No.09 - September (2009 vol.58)
pp: 1250-1258
Fengxiang Zhang , University of York, York
Alan Burns , University of York, York
Real-time scheduling is the theoretical basis of real-time systems engineering. Earliest Deadline First (EDF) is an optimal scheduling algorithm for uniprocessor real-time systems. Existing results on an exact schedulability test for EDF task systems with arbitrary relative deadlines need to calculate the processor demand of the task set at every absolute deadline to check if there is an overflow in a specified time interval. The resulting large number of calculations severely restricts the use of EDF in practice. In this paper, we propose new results on necessary and sufficient schedulability analysis for EDF scheduling; the new results reduce, exponentially, the calculation times, in all situations, for schedulable task sets, and in most situations, for unschedulable task sets. For example, a 16-task system that in the previous analysis had to check 858,331 points (deadlines) can, with the new analysis, be checked at just 12 points. There are no restrictions on the new results: each task can be periodic or sporadic, with relative deadline, which can be less than, equal to, or greater than its period, and task parameters can range over many orders of magnitude.
Multiprocessing/multiprogramming/multitasking, scheduling, real-time and embedded systems.
Fengxiang Zhang, Alan Burns, "Schedulability Analysis for Real-Time Systems with EDF Scheduling", IEEE Transactions on Computers, vol.58, no. 9, pp. 1250-1258, September 2009, doi:10.1109/TC.2009.58
[1] K. Albers and F. Slomka , “An Event Stream Driven Approximation for the Analysis of Real-Time Systems,” Proc. 16th Euromicro Conf. Real-Time Systems, pp. 187-195, 2004.
[2] N.C. Audsley , A. Burns , M. Richardson , K.W. Tindell , and A.J. Wellings , “Applying New Scheduling Theory to Static Priority Pre-Emptive Scheduling,” Software Eng. J., vol. 8, no. 5, pp. 284-292, 1993.
[3] S.K. Baruah , A.K. Mok , and L.E. Rosier , “Preemptively Scheduling Hard-Real-Time Sporadic Tasks on One Processor,” Proc. 11th IEEE Real-Time System Symp., pp. 182-190, 1990.
[4] S.K. Baruah , L.E. Rosier , and R.R. Howell , “Algorithms and Complexity Concerning the Preemptive Scheduling of Periodic Real-Time Tasks on One Processor,” J. Real-Time Systems, vol. 4, no. 2, pp. 301-324, 1990.
[5] S.K. Baruah , R.R. Howell , and L.E. Rosier , “Feasibility Problems for Recurring Tasks on One Processor,” Theoretical Computer Science, vol. 118, pp. 3-20, 1993.
[6] E. Bini and G.C. Buttazzo , “Measuring the Performance of Schedulability Tests,” J. Real-Time Systems, vol. 30, nos. 1/2, pp.129-154, 2005.
[7] G.C. Buttazzo , “Real-Time Scheduling and Resource Management,” Handbook of Real-Time and Embedded Systems. Chapman & Hall/CRC, 2008.
[8] S. Chakraborty , S. Kunzli , and L. Thiele , “Approximate Schedulability Analysis,” Proc. IEEE Real-Time Systems Symp., pp. 159-168, 2002.
[9] M.L. Dertouzos , “Control Robotics: The Procedural Control of Physical Processes,” Proc. Int'l Federation for Information Processing (IFIP) Congress, pp. 807-813, 1974.
[10] M. Devi , “An Improved Schedulability Test for Uniprocessor Periodic Task Systems,” Proc. 15th Euromicro Conf. Real-Time Systems, pp. 23-30, 2003.
[11] L. George , N. Rivierre , and M. Spuri , “Preemptive and Non-Preemptive Real-Time Uniprocessor Scheduling,” Technical Report 2966, INRIA, 1996.
[12] H. Hoang , G. Buttazzo , M. Jonsson , and S. Karlsson , “Computing the Minimum EDF Feasible Deadline in Periodic Systems,” Proc. 12th IEEE Int'l Conf. Embedded and Real-Time Computing Systems and Applications, pp. 125-134, 2006.
[13] M. Joseph and P.K. Pandya , “Finding Response Times in a Real-Time System,” The Computer J., vol. 29, no. 5, pp. 390-395, 1986.
[14] J.Y.-T. Leung and M.L. Merrill , “A Note on Preemptive Scheduling of Periodic, Real-Time Tasks,” Information Processing Letters, vol. 11, no. 3, pp. 115-118, 1980.
[15] C.L. Liu and J.W. Layland , “Scheduling Algorithm for Multiprogramming in a Hard Real-Time Environment,” J. ACM, vol. 20, no. 1, pp. 40-61, 1973.
[16] J.W.S. Liu , Real-Time Systems. Prentice-Hall, 2000.
[17] R.I. Davis and A. Burns , “Efficient Exact Schedulability Tests for Fixed Priority Real-Time Systems,” IEEE Trans. Computers, vol. 57, no. 9, pp. 1261-1271, Apr. 2008.
[18] I. Ripoll , A. Crespo , and A.K. Mok , “Improvement in Feasibility Testing for Real-Time Tasks,” J. Real-Time Systems, vol. 11, no. 1, pp. 19-39, 1996.
[19] M. Spuri , “Analysis of Deadline Schedule Real-Time Systems,” Technical Report 2772, INRIA, 1996.
[20] F. Zhang and A. Burns , “Schedulability Analysis for Real-Time Systems with EDF Scheduling,” Technical Report YCS-426-2008, Dept. of Computer Science, Univ. of York, 2008.
15 ms
(Ver 2.0)

Marketing Automation Platform Marketing Automation Tool