DocumentCode :
2331609
Title :
Pessimism in the stochastic analysis of real-time systems: concept and applications
Author :
Diaz, J.L. ; Lopez, J.M. ; García, Manuel ; Campos, Ana Margarida ; Kim, Kanghee ; Bello, Lucia Lo
Author_Institution :
Depto. de Informatica, Univ. de Oviedo, Gijon, Spain
fYear :
2004
fDate :
5-8 Dec. 2004
Firstpage :
197
Lastpage :
207
Abstract :
The exact stochastic analysis of most real-time systems is becoming unaffordable in current practice. On one side, the exact calculation of the response time distribution of the tasks is not possible except for simple periodic and independent task sets. On the other side, in practice, tasks introduce complexities like release jitter, blocking in shared resources, stochastic dependencies, etc, which can not be handled by the periodic and independent task set model. This paper introduces the concept of pessimism in the stochastic analysis of real-time systems in the following sense: the exact probability of missing any deadline is always lower than that derived from the pessimistic analysis. Therefore, if real-time constraints are expressed as probabilities of missing deadlines, the pessimistic stochastic analysis provides safe results. Some applications of the pessimism concept are presented. Firstly, the practical problems that arise in the stochastic analysis of periodic and independent task sets are addressed. Secondly, we extend to the stochastic case some well known techniques of the deterministic analysis, such as the blocking in shared resources, and the task priority assignment.
Keywords :
computational complexity; probability; real-time systems; stochastic processes; deterministic analysis; pessimistic stochastic analysis; real-time systems; task response time distribution; Computer science; Delay; Jitter; Random variables; Real time systems; Scheduling algorithm; Stochastic processes; Stochastic systems; Telecommunications; Traffic control;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Real-Time Systems Symposium, 2004. Proceedings. 25th IEEE International
ISSN :
1052-8725
Print_ISBN :
0-7695-2247-5
Type :
conf
DOI :
10.1109/REAL.2004.41
Filename :
1381307
Link To Document :
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