Scheduling Offset-Free Systems Under FIFO Priority Protocol

Authors Matheus Ladeira , Emmanuel Grolleau , Fabien Bonneval, Gautier Hattenberger , Yassine Ouhammou , Yuri Hérouard

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Author Details

Matheus Ladeira
  • ISAE ENSMA, Chasseneuil, France
  • University of Poitiers, France
Emmanuel Grolleau
  • ISAE-ENSMA, Chasseneuil, France
  • University of Poitiers, France
Fabien Bonneval
  • Ecole Nationale de l'Aviation Civile, Toulouse, France
Gautier Hattenberger
  • Ecole Nationale de l'Aviation Civile, Toulouse, France
Yassine Ouhammou
  • ISAE-ENSMA, Chasseneuil, France
  • University of Poitiers, France
Yuri Hérouard
  • ISAE-ENSMA, Chasseneuil, France

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Matheus Ladeira, Emmanuel Grolleau, Fabien Bonneval, Gautier Hattenberger, Yassine Ouhammou, and Yuri Hérouard. Scheduling Offset-Free Systems Under FIFO Priority Protocol. In 34th Euromicro Conference on Real-Time Systems (ECRTS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 231, pp. 11:1-11:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


On UAVs, telemetry messages are often sent following a FIFO schedule, and some messages, depending on the FIFO queue state may suffer long delays, and can even be lost if the FIFO queue is full. Considering the high complexity of the problem of assigning offsets to periodic tasks, we propose a new heuristic, called GCD+, that we compare to the methods of the state of the art, showing that GCD+ significantly outperforms them on synthetic tasks sets. Then we use a real UAV use case, based on Paparazzi autopilot, to show that GCD+ behaves well. The proposed algorithm is meant to be the new Paparazzi’s automatic offset assignment method for messages.

Subject Classification

ACM Subject Classification
  • Computer systems organization → Real-time system architecture
  • Computer systems organization → Embedded software
  • Scheduling
  • non-preemptible
  • heuristics
  • FIFO
  • autopilot


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