Dynamic Real-time Scheduling of Firm Periodic Tasks with Hard and Soft Aperiodic Tasks

In this paper, we address the problem of the dynamic scheduling of skippable periodic task sets (i.e., period tasks allowing occasional skips of instances), together with aperiodic tasks. Scheduling of tasks is handled thanks to the merging of two existing approaches: the Skip-Over task model and the EDL (Earliest Deadline as Late as possible) aperiodic task server. The objective is to provide two on-line scheduling algorithms, namely EDL-RTO and EDL-BWP, in order to minimize the average response time of soft aperiodic requests, while ensuring that the QoS (Quality of Service) of periodic tasks will never be less than a specified bound. We also extend our results to the acceptance of sporadic tasks (i.e., aperiodic tasks with deadlines). We show that these novel scheduling algorithms have better performance compared to related algorithms regarding aperiodic response time and acceptance ratio.

[1]  Marco Spuri,et al.  Efficient aperiodic service under earliest deadline scheduling , 1994, 1994 Proceedings Real-Time Systems Symposium.

[2]  Alan Burns,et al.  Scheduling slack time in fixed priority pre-emptive systems , 1993, 1993 Proceedings Real-Time Systems Symposium.

[3]  Theodore P. Baker,et al.  Aperiodic servers in a deadline scheduling environment , 2005, Real-Time Systems.

[4]  Parameswaran Ramanathan,et al.  A Dynamic Priority Assignement Technique for Streams with (m, k)-Firm Deadlines , 1995, IEEE Trans. Computers.

[5]  J.A. Stankovic,et al.  Misconceptions about real-time computing: a serious problem for next-generation systems , 1988, Computer.

[6]  James W. Layland,et al.  Scheduling Algorithms for Multiprogramming in a Hard-Real-Time Environment , 1989, JACM.

[7]  Maryline Chetto,et al.  Dynamic scheduling of real-time tasks under precedence constraints , 1990, Real-Time Systems.

[8]  Marco Spuri,et al.  Scheduling aperiodic tasks in dynamic priority systems , 1996, Real-Time Systems.

[9]  Jay K. Strosnider,et al.  The Deferrable Server Algorithm for Enhanced Aperiodic Responsiveness in Hard Real-Time Environments , 1987, IEEE Trans. Computers.

[10]  Maryline Chetto,et al.  An optimal algorithm for guaranteeing sporadic tasks in hard real-time systems , 1990, Proceedings of the Second IEEE Symposium on Parallel and Distributed Processing 1990.

[11]  Giorgio C. Buttazzo,et al.  Exploiting skips in periodic tasks for enhancing aperiodic responsiveness , 1997, Proceedings Real-Time Systems Symposium.

[12]  John P. Lehoczky,et al.  An optimal algorithm for scheduling soft-aperiodic tasks in fixed-priority preemptive systems , 1992, [1992] Proceedings Real-Time Systems Symposium.

[13]  Maryline Silly,et al.  The EDL Server for Scheduling Periodic and Soft Aperiodic Tasks with Resource Constraints , 1999 .

[14]  Giorgio C. Buttazzo,et al.  Optimal Deadline Assignment for Scheduling Soft Aperiodic Tasks in Hard Real-Time Environments , 1999, IEEE Trans. Computers.

[15]  Ismael Ripoll,et al.  An Optimal Algorithm for Scheduling Soft Aperiodic Tasks in Dynamic-Priority Preemptive Systems , 1997, IEEE Trans. Software Eng..

[16]  Lui Sha,et al.  Aperiodic task scheduling for Hard-Real-Time systems , 2006, Real-Time Systems.

[17]  Joseph Y.-T. Leung,et al.  On the complexity of fixed-priority scheduling of periodic, real-time tasks , 1982, Perform. Evaluation.

[18]  Dennis Shasha,et al.  Skip-Over: algorithms and complexity for overloaded systems that allow skips , 1995, Proceedings 16th IEEE Real-Time Systems Symposium.

[19]  Giorgio C. Buttazzo,et al.  Minimizing Aperiodic Response Times in a Firm Real-Time Environment , 1999, IEEE Trans. Software Eng..

[20]  Jane W.-S. Liu,et al.  Algorithms and optimality of scheduling soft aperiodic requests in fixed-priority preemptive systems , 2004, Real-Time Systems.

[21]  Giorgio C. Buttazzo,et al.  Optimal scheduling for fault-tolerant and firm real-time systems , 1998, Proceedings Fifth International Conference on Real-Time Computing Systems and Applications (Cat. No.98EX236).

[22]  Marco Spuri,et al.  Robust aperiodic scheduling under dynamic priority systems , 1995, Proceedings 16th IEEE Real-Time Systems Symposium.

[23]  Maryline Chetto,et al.  Some Results of the Earliest Deadline Scheduling Algorithm , 1989, IEEE Transactions on Software Engineering.

[24]  Maryline Chetto,et al.  The EDL Server for Scheduling Periodic and Soft Aperiodic Tasks with Resource Constraints , 2004, Real-Time Systems.

[25]  Jay K. Strosnider,et al.  ENHANCED APERIODIC RESPONSIVENESS IN HARD REAL-TIME ENVIRONMENTS. , 1987, RTSS 1987.