A T-time Petri net extension for real time-task scheduling modeling

International audienceIn order to analyze whether timing requirements of a real-time application are met, we propose an extension of the T-time {Petri} net model which takes into account the scheduling of the software tasks distributed over a multi-processor hardware architecture. The paper is concerned with static priority pre-emptive based scheduling. This extension consists in mapping into the {Petri} net model the way the different schedulers of the system activate or suspend the tasks. This relies on the introduction of two new attributes for the places (allocation and priority). First we give the formal semantics of this extended model as a timed transition system (TTS). Then we propose a method for its analysis consisting in the computation of the state class graph. Thus the verification of timing properties can be conducted (possibly together with an observator) and comes to analyze the such obtained state class grap

Simulation of Real-Time Scheduling with Various Execution Time Models

Presented during the Work-in-Progress session (WiP session)International audienceIn this paper, we present SimSo, a simulator that aims at facilitating the design of experimental evaluations for real-time scheduling algorithms. Currently, more than twenty-five algorithms were implemented. Special attention is paid to the execution time model of tasks. We show that the worst-case execution time for experimental simulation can introduce a bias in evaluation and we discuss as a work in progress how cache effects could be taken into consideration in the simulation

Une contrainte globale pour l'ordonnançabilité des tâches temps réel dur

Résoudre des problèmes de placement de tâches temps réel est un challenge pour les communautés issues de la recherche opérationnelle et de la programmation par contraintes (ppc). La difficulté principale de tels problèmes réside dans la prise en considération des contraintes temporelles spécifiques aux systèmes temps réel. Ces contraintes sont difficilement exprimables pour un solveur et méritent donc un traitement particulier. Dans cet article, nous proposons une approche novatrice qui introduit ces aspects temporels par le biais d'une contrainte globale et donc directement dans les mécanismes de la ppc. Nous finalisons l'étude en montrant à travers de nombreuses expérimentations que cette méthode est viable et efficace

Ordonnancement temps réel multiprocesseur partitionné et programmation par contraintes

National audienc

STORM – Designer guide 3.3

Guide technique - http://storm.rts-software.org/download/Designer-guideV3.3_version1.pd

Simulation of Real-Time Multiprocessor Scheduling with Overheads

International audienceNumerous scheduling algorithms were and still are designed in order to handle multiprocessor architectures, raising new issues due to the complexity of such architectures. Moreover, evaluating them is difficult without a real and complex implementation. Thus, this paper presents a tool that intends to facilitate the study of schedulers by providing an easy way of prototyping. Compared to the other scheduling simulators, this tool takes into account the impact of the caches through statistical models and includes direct overheads such as context switches and scheduling decisions

Simulation d'ordonnancement temps réel avec prise en compte de l'impact des caches

National audienceAfin de prendre en charge au mieux les supports d'exécution multiprocesseurs pour les systèmes temps réel, de nombreuses politiques d'ordonnancement ont été proposées. Cependant, l'augmentation de la complexité de ces architectures rend plus difficile l'évaluation et la comparaison de ces algorithmes. Notre objectif est de faciliter ce travail en fournissant un outil de simulation qui intègre certains aspects pouvant avoir un impact important sur les systèmes réels, à savoir, les caches, la durée de prise de décision d'ordonnancement et les changements de contexte

Overhead control heuristics in Boundary Fair real-time multiprocessor scheduling

International audienc