Running real time distributed simulations under Linux and CERTI

This paper presents some experiments and some results to enforce real time distributed simulations in accordance with the High Level Architecture (HLA). Simulations were run by using CERTI, an open source middleware, as the Run Time Infrastructure (RTI). Models were distributed over computers under various available versions of the 2.6 Linux kernel. Studies and experiments relied on a real case study. The chosen case study was the simulation of an "in formation" flight of observation satellites. This case study brings up some real applicative needs in real time distributed simulations and real configurations of simulators and models. Two simulations of "in formation" flight of satellites were studied. The study consisted in modeling the behaviour of the simulators and in running these models by using various kernel or middleware operating mechanisms and services. Time measurements were performed at each test giving some results on the ability of the simulation to meet its real time requirements

HLA high performance and real-time simulation studies with CERTI

Our work takes place in the context of the HLA standard and its application in real-time systems context. Indeed, current HLA standard is inadequate for taking into consideration the different constraints involved in real-time computer systems. Many works have been invested in order to provide real-time capabilities to Run Time Infrastructures (RTI). This paper describes our approach focusing on achieving hard real-time properties for HLA federations through a complete state of the art on the related domain. Our paper also proposes a global bottom up approach from basic hardware and software basic requirements to experimental tests for validation of distributed real-time simulation with CERTI

CERTI, an Open Source RTI, why and how

CERTI is an HLA RTI developed since 1996 by ONERA, the French Aerospace Lab. The initial purpose of CERTI was to develop a home made RTI in order to: learn HLA usage and HLA RTI internals (e.g. time management), have total control over source code in order to use this particular RTI with specific modifications in several research projects (security mechanism, multi-resolution, high performance distributed simulation...). CERTI became open source in 2002: https://savannah.nongnu.org/projects/certi. Since then, Open Source CERTI project has had variable activity periods, mostly driven by research project needs and funds. CERTI development has started again since the end of 2006, with an increased interest from the open source user community. After a brief status survey of CERTI, this presentation will focus on the Open Source objectives of CERTI and explain why this is not a product but a project driven OSS initiative, pushed by a Public establishment like ONERA. We will further explain how open sourceness CERTI stimulates its development and the community itself and why every stakeholder benefits from this

The ROSACE Case Study: From Simulink Specification to Multi/Many-Core Execution

This paper presents a complete case study - named ROSACE for Research Open-Source Avionics and Control Engineering - that goes from a baseline flight controller, developed in MATLAB/SIMULINK, to a multi-periodic controller executing on a multi/many-core target. The interactions between control and computer engineers are highlighted during the development steps, in particular by investigating several multi-periodic configurations. We deduced ways to improve the discussion between engineers in order to ease the integration on the target. The whole case study is made available to the community under an open-source license

Developing critical embedded systems on multicore architectures: the Prelude-SchedMCore toolset

International audienceIn this paper we present an end-to-end framework for the design and the implementation of embedded systems on a symmetric multicore. The developer first specifies the system using the \prelude language, a formal real-time architecture description language. The Prelude compiler then translates the program into a set of communicating periodic tasks that preserves the semantics of the original program. The schedulability analysis is performed by the SchedMCore analyzer. If the program is schedulable, it can finally be executed on the target multicore architecture using the \schedmcore execution environment

Architectural performance analysis of FPGA synthesized LEON processors

Current processors have gone through multiple internal opti- mization to speed-up the average execution time e.g. pipelines, branch prediction. Besides, internal communication mechanisms and shared resources like caches or buses have a sig- nificant impact on Worst-Case Execution Times (WCETs). Having an accurate estimate of a WCET is now a challenge. Probabilistic approaches provide a viable alternative to single WCET estimation. They consider WCET as a probabilistic distribution associated to uncertainty or risk. In this paper, we present synthetic benchmarks and associated analysis for several LEON3 configurations on FPGA targets. Benchmarking exposes key parameters to execution time variability allowing for accurate probabilistic modeling of system dynamics. We analyze the impact of architecture- level configurations on average and worst-case behaviors

Un RTI Open Source, pourquoi et comment?

CERTI est une infrastructure d'exécution, pour les simulations distribuées suivant la norme HLA, développée à l'ONERA depuis 1996. Les objectifs initiaux étaient multiples : comprendre et utiliser HLA, effectuer des recherches en simulation distribuée qui nécessitaient la maîtrise de l'infrastructure d'exécution utilisée. CERTI devient un logiciel libre open source en 2002 et nous détaillons les objectifs et les retombées de cette transition

Reconfigurable IMA platform: from safety assessment to test scenarios on the SCARLETT demonstrator

International audienceThe next generation of IMA platforms should include reconfiguration capabilities in order to limit the effect of some hardware failures on aircraft operational reliability. The contribution of this paper is to describe the safety assessment process from the safety assessment on the preliminary design of a reconfigurable IMA architecture to the execution of the failure scenarios on the SCARLETT demonstrator

Programmation parallèle orientée objet et réutilisabilité appliquée à l'algèbre linéaire

Version finale du 28 janvier 2001.The primary thesis topic is to study how object-oriented technologies may bring to scientific applications all the benefits they bring to traditionnal sequential application like: better reuse and longer software life, design methodology, cleaner realization... The main scientific computing constraint, which is performance is kept in mind.After a survey of parallel and object-oriented programming concepts, the design and realization of a parallel linear algebra library is presented. We study two different object-oriented approaches. The first use C++// language, a concurrent object-oriented language derived from C++, which implements an active object model. The second is the use of MPI through a minimal object-oriented layer realized in C++.Both of them, raise problems, regarding performance and/or sequential/parallel reuse. We solve these problems.We propose a shared on read mecanism applicable to any active object model, showing its efficiency for our applications. The second approach leads us to the new concepts of matrix shapeand shaped matrices which enable us to reach our sequential/parallel reuse objectives.In the end, the implemented design enable us to instantiate both a sequential and parallel version of our linear algebra algorithms from the very same piece of code. The resulting parallel and sequential applications both exhibit satisfying performances.L'objectif de cette thèse est d'examiner comment les technologies orientées-objet peuvent apporter aux applications scientifiques tout ce qu'elles ont apporté dans la programmation des machines séquentielles: une meilleure réutilisabilité et pérennité des codes, des démarches méthodologiques de conception et de réalisation claires... La contrainte du calcul scientifique parallèle de ne pas sacrifier les performances devant être respectée.Après une revue des moyens de programmation parallèle et desconcepts objets, la conception et la réalisation d'une bibliothèque parallèle d'algèbre linéaire orientée-objet sont présentées. Nous étudions deux moyens de programmation parallèle, le premier, C++//, est un LAO parallèle à objets actifs dérivé de C++, le second est l'utilisation de MPI au travers d'une surcouche objet minimale.Ces deux approches objets posent des problèmes soit de performances soit de réutilisabilité séquentielle/parallèle qui sont présentés et résolus.Nous proposons notamment un mécanisme simple de partage en lecture pour les modèles à objets actifs, en montrant son utilité en terme de performances de nos applications. Suite à la seconde approche nous définissons les notions de formes de matrices et de matrices avec forme qui permettent d'atteindre nos objectifs de réutilisabilité séquentielle/parallèle.Au final, la conception et la réalisation permettent d'instancier, à partir du même code [séquentiel] d'algèbre linéaire, une version séquentielle et parallèle offrant des performances satisfaisantes

Programmation parallèle orientée objet et réutilisabilité appliquée à l'algèbre linéaire

L'objectif de cette thèse est d'examiner comment les technologies orientées-objet peuvent apporter aux applications scientifiques tout ce qu'elles ont apporté dans la programmation des machines séquentielles : une meilleure réutilisabilité et pérennité des codes, des démarches méthodologiques de conception et de réalisation claires... La contrainte du calcul scientifique parallèle de ne pas sacrifier les performances devant être respectée. Après une revue des moyens de programmation parallèle et des concepts objets, la conception et la réalisation d'une bibliothèque parallèle d'algèbre linéaire orientée-objet sont présentées. Nous étudions deux moyens de programmation parallèle, le premier, C++//, est un LAO parallèle à objets actifs dérivé de C++, le second est l'utilisation de MPI au travers d'une surcouche objet minimale. Ces deux approches objets posent des problèmes soit de performances soit de réutilisabilité séquentielle/parallèle qui sont présentés et résolus. Nous proposons notamment un mécanisme simple de partage en lecture pour les modèles à objets actifs, en montrant son utilité en terme de performances de nos applications. Suite à la seconde approche nous définissons les notions de formes de matrices et de matrices avec forme qui permettent d'atteindre nos objectifs de réutilisabilité séquentielle/parallèle. Au final, la conception et la réalisation permettent d'instancier, à partir du même code[séquentiel]d'algèbre linéaire, une version séquentielle et parallèle offrant des performances satisfaisantes.VERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceF