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Replica determinism and flexible scheduling in hard real-time dependable systems

Poledna, S, Burns, A, Wellings, A and Barrett, P (2000) Replica determinism and flexible scheduling in hard real-time dependable systems. IEEE Transactions on Computers. pp. 100-111. ISSN 0018-9340

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Abstract

Fault-tolerant real-time systems are typically based on active replication where replicated entities are required to deliver their outputs in an identical order within a given time interval. Distributed scheduling of replicated tasks, however, violates this requirement if on-line scheduling, preemptive scheduling, or scheduling of dissimilar replicated task sets is employed. This problem of inconsistent task outputs has been solved previously by coordinating the decisions of the local schedulers such that replicated tasks are executed in an identical order. Global coordination results either in an extremely high communication effort to agree on each schedule decision or in an overly restrictive execution model where on-line scheduling, arbitrary preemptions, and nonidentically replicated task sets are not allowed. To overcome these restrictions, a new method, called timed messages, is introduced. Timed messages guarantee deterministic operation by presenting consistent message versions to the replicated tasks. This approach is based on simulated common knowledge and a sparse time base. Timed messages are very effective since they neither require communication between the local scheduler nor do they restrict usage of on-line flexible scheduling, preemptions and nonidentically replicated task sets.

Item Type: Article
Copyright, Publisher and Additional Information: Copyright © 2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Keywords: distributed real-time systems, fault tolerance, distributed operating systems, replica determinism, distributed scheduling, flexible scheduling, COMMON KNOWLEDGE, CLOCKS
Academic Units: The University of York > Computer Science (York)
Depositing User: Repository Officer
Date Deposited: 18 Jul 2006
Last Modified: 17 Oct 2013 14:38
Published Version: http://dx.doi.org/10.1109/12.833107
Status: Published
Refereed: Yes
Related URLs:
URI: http://eprints.whiterose.ac.uk/id/eprint/1451

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