Scheduling of Time-Triggered Real-Time Systems

  • Authors:
  • Klaus Schild;Jörg Würtz

  • Affiliations:
  • DaimlerChrysler AG, Research and Technology, Alt-Moabit 96a, D-10559 Berlin, Germany;IBM Germany, Postfach 1380, D-71003 Böblingen, Germany

  • Venue:
  • Constraints
  • Year:
  • 2000

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Abstract

Thispaper introduces a new class of applications for constraint programming.This new type of application originates out of a special classof real-time systems, enjoying increasing popularity in areassuch as automotive electronics and aerospace industry. Real-timesystems of this kind are time triggered in the sense that theiroverall behavior is globally controlled by a recurring clocktick. Being able to compute an appropriate pre-runtime scheduleautomatically is the major challenge for such an architecture.What makes this specific off-line scheduling problem somewhatuntypical is that a potentially indefinite, periodic processinghas to be mapped onto a single time window. In this article wewill show how this problem can be solved by constraint programmingand we will describe which techniques from traditional schedulingand real-time computing led to success and which failed whenconfronted with a large-scale application of this type. The techniquesthat proved to be the most successful were special global constraintsand an elaborate search heuristics from Operations Research.Also for finding a valid schedule mere serialization is shownto be sufficient. The actual implementation was done in the concurrentconstraint programming language Oz.