A generic approach to schedulability analysis of real-time tasks

  • Authors:

  • Elena Fersman;Wang Yi

  • Affiliations:

  • Uppsala University, Department of Information Technology P.O. Box 337, S-751 05 Uppsala, Sweden;Uppsala University, Department of Information Technology P.O. Box 337, S-751 05 Uppsala, Sweden

  • Venue:
  • Nordic Journal of Computing
  • Year:
  • 2004

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Abstract

In off-line schedulability tests for real time systems, tasks are usually assumed to be periodic, i.e. they are released with fixed rates. To relax the assumption of complete knowledge on arrival times, we propose to use timed automata to describe task arrival patterns. In a recent work, it is shown that for fixed priority scheduling strategy and tasks with only timing constraints (i.e. execution time and deadline), the schedulability of such models can be checked by reachability analysis on timed automata with two clocks.In this paper, we extend the above result to deal with precedence and resource constraints. This yields a unified task model, which is expressive enough to describe concurrency, synchronization, and tasks that may be periodic, aperiodic, preemptive or nonpreemptive with (or without) combinations of timing, precedence, and resource constraints. We present an operational semantics for the model, and show that the related schedulability analysis problem can be solved efficiently using the same technique. The presented results have been implemented in the TIMES tool for automated schedulability analysis.