Bernat, G., Burns, A. and Liamosi, A. (2001) Weakly hard real-time systems. IEEE Transactions on Computers, 50 (4). pp. 308-321. ISSN 0018-9340
Abstract
In a hard real-time system, it is assumed that no deadline is missed, whereas, in a soft or firm real-time system, deadlines can be missed, although this usually happens in a nonpredictable way. However, most hard real-time systems could miss some deadlines provided that it happens in a known and predictable way. Also, adding predictability on the pattern of missed deadlines for soft and firm real-time systems is desirable, for instance, to guarantee levels of quality of service. We introduce the concept of weakly hard real-time systems to model real-time systems that can tolerate a clearly specified degree of missed deadlines. For this purpose, we define four temporal constraints based on determining a maximum number of deadlines that can be missed during a window of time (a given number of invocations). This paper provides the theoretical analysis of the properties and relationships of these constraints. It also shows the exact conditions under which a constraint is harder to satisfy than another constraint. Finally, results on fixed priority scheduling and response-time schedulability tests for a wide range of process models are presented
Metadata
Item Type: | Article |
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Authors/Creators: |
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Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Computer Science (York) |
Depositing User: | York RAE Import |
Date Deposited: | 06 Aug 2009 13:32 |
Last Modified: | 06 Aug 2009 13:32 |
Published Version: | http://dx.doi.org/10.1109/12.919277 |
Status: | Published |
Publisher: | IEEE Institute of Electrical and Electronics |
Identification Number: | 10.1109/12.919277 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:6199 |