Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System
• SEI Report
Publisher
Software Engineering Institute
CMU/SEI Report Number
CMU/SEI-89-TR-011Topic or Tag
Abstract
A real-time system consists of both aperiodic and periodic tasks. Periodic tasks have regular arrival times and hard deadlines. Aperiodic tasks have irregular arrival times and either soft or hard deadlines. In this paper, we present a new algorithm, the Sporadic Server algorithm, that greatly improves response times for soft-deadline aperiodic tasks and can guarantee hard deadlines for both periodic and aperiodic tasks. The operation of the Sporadic Server algorithm, its performance, and schedulability analysis are discussed and compared with previous, published aperiodic service algorithms.
Cite This SEI Report
Sprunt, B., Sha, L., & Lehoczky, J. (1989, April 1). Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System. (SEI Report CMU/SEI-89-TR-011). Retrieved June 21, 2026, from https://www.sei.cmu.edu/library/scheduling-sporadic-and-aperiodic-events-in-a-hard-real-time-system/.
@techreport{sprunt_1989,
author={Sprunt, Brinkley and Sha, Lui and Lehoczky, John},
title={Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System},
month={Apr},
year={1989},
number={{CMU/SEI-89-TR-011},
institution={Software Engineering Institute, Carnegie Mellon University},
url={https://www.sei.cmu.edu/library/scheduling-sporadic-and-aperiodic-events-in-a-hard-real-time-system/},
note={Accessed: 2026-Jun-21}
}
Sprunt, Brinkley, Lui Sha, and John Lehoczky. "Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System." (CMU/SEI-89-TR-011). Software Engineering Institute, Carnegie Mellon University. Software Engineering Institute, April 1, 1989. https://www.sei.cmu.edu/library/scheduling-sporadic-and-aperiodic-events-in-a-hard-real-time-system/.
B. Sprunt, L. Sha, and J. Lehoczky, "Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System," Software Engineering Institute, Carnegie Mellon University. Software Engineering Institute, SEI Report CMU/SEI-89-TR-011, 1-Apr-1989 [Online]. Available: https://www.sei.cmu.edu/library/scheduling-sporadic-and-aperiodic-events-in-a-hard-real-time-system/. [Accessed: 21-Jun-2026].
Sprunt, Brinkley, Lui Sha, and John Lehoczky. "Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System." (SEI Report CMU/SEI-89-TR-011). Software Engineering Institute, Carnegie Mellon University, Software Engineering Institute, 1 Apr. 1989. https://www.sei.cmu.edu/library/scheduling-sporadic-and-aperiodic-events-in-a-hard-real-time-system/. Accessed 21 Jun. 2026.
Sprunt, Brinkley; Sha, Lui; & Lehoczky, John. Scheduling Sporadic and Aperiodic Events in a Hard Real-Time System. CMU/SEI-89-TR-011. Software Engineering Institute. 1989. https://www.sei.cmu.edu/library/scheduling-sporadic-and-aperiodic-events-in-a-hard-real-time-system/