Task Allowance for Failure Prevention of Fixed Priority Scheduled Real-Time Java Systems

L. Bougueroua, L. George, and S. Midonnet (France)

Keywords

: Allowance, realtime scheduling, feasibility analysis, fault tolerance, FP/HPF.

Abstract

Correct real-time system dimensioning depends on the accuracy of the determination of task execution duration, which may be variable and difficult to estimate. This is still true and critical in the case of real-time Java applications, where the underlying architecture is a priori unknown and where the variability of execution duration can generate timeliness and logic failures. In this paper, we present a solution to prevent timeliness failures, using a fault detection system. The solution is based on the concept of allowance. The allowance is the maximum duration a task can proceed its execution without compromising the real-time constraints of all the tasks. We show how to integrate this mechanism into existing feasibility conditions for fixed priority scheduling.

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