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Section: New Results
Multiprocessor Real-Time Scheduling
Participants : Yves Sorel, Laurent George, Dumitru Potop-Butucaru, Falou Ndoye, Aderraouf Benyahia, Cécile Stentzel, Meriem Zidouni.
Multiprocessor Partitioned Scheduling with Exact Preemption Cost
We finalized the work started in previous years on multiprocessor scheduling of preemptive independent real-time tasks with exact preemption cost [43] .
This year we proposed a heuristic for the multiprocessor scheduling of preemptive dependent real-time tasks with exact preemption cost. We chose the partitioned approach that avoids migration of tasks and allows the utilization of the uniprocessor schedulability condition, previously proposed, that takes into account the exact preemption cost. In addition, this schedulability condition takes into account the inter-processor communications and guarantees that no data is lost. The result of such an off-line scheduling provided by the heuristic, is a scheduling table for every processor which includes also inter-processor communication tasks. We compared our multiprocessor scheduling heuristic with a Branch & Bound exact algorithm using the same schedulability condition. Our heuristic provides similar results and is very much faster.
Multiprocessor Semi-Partitioned Mixed Criticality Scheduling
We mainly focused on the mixed criticality scheduling problem applied to semi-partitioned scheduling considering a static pattern of migration for jobs. We have studied this problem in the context of Mixed Criticality (MC) scheduling, a promising approach that can be used to take into account applications of different criticality levels on the same platform. The goal of MC approach is to better utilize computing resources by allowing low criticality tasks to execute in conjunction with high criticality tasks when the system criticality is not high.
Gateway with Modeling Languages for Certified Code Generation
This work was carried out in the P FUI project 8.2.2 . We defined a SynDEx UML profile for functional specifications. We developed a gateway between the P pivot formalism and SynDEx. This gateway deals with the data-flow modeling part of the P formalism which is compliant with the Simulink subset blocks supported by the P project, except for the IF, FOR, MERGE and MUX blocks. Presently, we enhance the gatetway to include these blocks and we colloborate with the other partners to define the architectural part of the P formalism. This part is intended to replace the non functional specifications, presently described with the UML profile MARTE (Modeling and Analysis of Real-Time Embedded Systems).
SynDEx updates with new results
We released an alpha version of SynDEx V8. This version is based on a new textual language whose compiler may be launched with commandes-lines featuring various options. In Syndex V8, the adequation heuristic which performs the multiprocessor real-time schedulability analysis on multi-periodic applications, is based on the theorems and algorithms provided in the Mohamed Marouf's thesis defended last year in the team. These algorithms have been deeply improved for better consideration of data dependencies in the case of multiprocessor architectures. On the other hand, the new heuristic generates a scheduling table composed of, in addition to the usual permanent phase, a transient phase that takes into account the distribution constraints defined by the user in the multi-periodic applications as well as in the mono-periodic applications.