Nicolas Markey

Résumé

Formal methods (e.g. Timed Automata or Linear Hybrid Automata) can be used to analyse a real-time system by performing a reachability analysis on the model. The advantage of using formal methods is that they are more expressive than classical analytic models used in schedulability analysis. For example, it is possible to express state-dependent behaviour, arbitrary activation patterns, etc.

In this paper we use the formalism of Linear Hybrid Automata to encode a hierarchical scheduling system. In particular, we model a dynamic server algorithm and the tasks contained within, abstracting away the rest of the system, thus enabling component-based scheduling analysis. We prove the correctness of the model and the decidability of the reachability analysis for the case of periodic tasks. Then, we compare the results of our model against classical schedulability analysis techniques, showing that our analysis performs better than analytic methods in terms of resource utilisation. We further present two case studies: a component with state-dependent tasks, and a simplified model of a real avionics system. Finally, through extensive tests with various configurations, we demonstrate that this approach is usable for medium size components.

@inproceedings{rtcsa2014-SLSFM,
  author =              {Sun, Youcheng and Lipari, Giuseppe and Soulat,
                         Romain and Fribourg, Laurent and Markey, Nicolas},
  title =               {Component-Based Analysis of Hierarchical Scheduling
                         using Linear Hybrid Automata},
  booktitle =           {{P}roceedings of the 20th {I}nternational
                         {C}onference on {R}eal-{T}ime {C}omputing {S}ystems
                         and {A}pplications ({RTCSA}'14)},
  acronym =             {{RTCSA}'14},
  publisher =           {IEEE Comp. Soc. Press},
  year =                {2014},
  month =               aug,
  doi =                 {10.1109/RTCSA.2014.6910502},
  abstract =            {Formal methods (e.g. Timed Automata or Linear Hybrid
                         Automata) can be used to analyse a real-time system
                         by performing a reachability analysis on the model.
                         The advantage of using formal methods is that they
                         are more expressive than classical analytic models
                         used in schedulability analysis. For example, it is
                         possible to express state-dependent behaviour,
                         arbitrary activation patterns,~etc.\par In this
                         paper we use the formalism of Linear Hybrid Automata
                         to encode a hierarchical scheduling system. In
                         particular, we model a dynamic server algorithm and
                         the tasks contained within, abstracting away the
                         rest of the system, thus enabling component-based
                         scheduling analysis. We prove the correctness of the
                         model and the decidability of the reachability
                         analysis for the case of periodic tasks. Then, we
                         compare the results of our model against classical
                         schedulability analysis techniques, showing that our
                         analysis performs better than analytic methods in
                         terms of resource utilisation. We further present
                         two case studies: a~component with state-dependent
                         tasks, and a simplified model of a real avionics
                         system. Finally, through extensive tests with
                         various configurations, we demonstrate that this
                         approach is usable for medium size components.},
}