12 research outputs found
A Compositional Approach for Schedulability Analysis of Distributed Avionics Systems
This work presents a compositional approach for schedulability analysis of
Distributed Integrated Modular Avionics (DIMA) systems that consist of
spatially distributed ARINC-653 modules connected by a unified AFDX network. We
model a DIMA system as a set of stopwatch automata in UPPAAL to verify its
schedulability by model checking. However, direct model checking is infeasible
due to the large state space. Therefore, we introduce the compositional
analysis that checks each partition including its communication environment
individually. Based on a notion of message interfaces, a number of message
sender automata are built to model the environment for a partition. We define a
timed selection simulation relation, which supports the construction of
composite message interfaces. By using assume-guarantee reasoning, we ensure
that each task meets the deadline and that communication constraints are also
fulfilled globally. The approach is applied to the analysis of a concrete DIMA
system.Comment: In Proceedings MeTRiD 2018, arXiv:1806.09330. arXiv admin note: text
overlap with arXiv:1803.1105
A Modeling Framework for Schedulability Analysis of Distributed Avionics Systems
This paper presents a modeling framework for schedulability analysis of
distributed integrated modular avionics (DIMA) systems that consist of
spatially distributed ARINC-653 modules connected by a unified AFDX network. We
model a DIMA system as a set of stopwatch automata (SWA) in UPPAAL to analyze
its schedulability by classical model checking (MC) and statistical model
checking (SMC). The framework has been designed to enable three types of
analysis: global SMC, global MC, and compositional MC. This allows an effective
methodology including (1) quick schedulability falsification using global SMC
analysis, (2) direct schedulability proofs using global MC analysis in simple
cases, and (3) strict schedulability proofs using compositional MC analysis for
larger state space. The framework is applied to the analysis of a concrete DIMA
system.Comment: In Proceedings MARS/VPT 2018, arXiv:1803.0866
Response-Time Analysis of Multipath Flows in Hierarchically-Scheduled Time-Partitioned Distributed Real-Time Systems
Modern industrial cyberphisical systems exhibit increasingly complex execution patterns like multipath end-to-end flows, that force the real-time community to extend the schedulability analysis methods to include these patterns. Only then it is possible to ensure that applications meet their deadlines even in the worst-case scenario. As a driving motivation, we present a real industrial application with safety requirements, that needs to be re-factored in order to leverage the features of new execution paradigms such as time partitioning. In this context we develop a new response-time analysis technique that provides the capacity of obtaining the worst-case response time of multipath flows in time-partitioned hierarchical schedulers and also in general fixed-priority (FP) real-time systems. We show that the results obtained with the new analysis reduce the pessimism of the currently used holistic analysis approach.This work was supported in part by the Doctorados Industriales 2018 program from the University of Cantabria and the Spanish Government and FEDER funds (AEI/FEDER, UE) under Grant TIN2017-86520-C3-3-R (PRECON-I4)
Heuristic Algorithm for Virtual Link Configuration in AFDX Networks
REACTION 2014. 3rd International Workshop on Real-time and Distributed Computing in Emerging Applications. Rome, Italy. December 2nd, 2014.As the AFDX networks have been increasingly employed for airborne networks, much research works have been conducted to support real-time service in a deterministic way. However, since they assumed the preconfigured networks where all involved parameters were already determined, the impact of configuration algorithm is not well explored. To solve this problem, in this paper, we focus on how to reduce the required bandwidth by configuring virtual link which logically consists of at least one or more application flows. To achieve this, new heuristic algorithms have been proposed by applying well-known greedy approach while taking essential constraints of AFDX networks into account. To evaulate the performance of proposed scheme, diverse case studies for airborne application flows are concerned and their number of virtual links as well as required bandwidth are compared.This work was supported by Basic Science Research Program (NRF-2013R1A1A2A10004587) through the National Research Foundation of Korea (NRF) funded by the Ministry of Education and the MSIP(Ministry of Science, ICT & Future Planning), Korea, under the ”SW master’s course of a hiring contract” support program (NIPA-2014-HB301-14- 1014) supervised by the NIPA(National IT Industry Promotion Agency).Publicad
Response Time Analysis for RT-MQTT Protocol Grounded on SDN
The current industry trend is to replace the use of custom components with standards-based Commercially available Off-The-Shelf (COTS) based hardware and protocols. Furthermore, the emergence of new industrial paradigms, such as Industry 4.0 and the Industrial Internet of Things, sets additional requirements regarding e.g. scale, transparency, agility, flexibility and efficiency. Therefore, in these domains, application layer protocols such as Message Queuing Telemetry Transport protocol (MQTT) are gaining popularity, in result of their simplicity, scalability, low resource-usage and decoupling between end nodes. However, such protocols were not designed for real-time applications, missing key features such as determinism and latency bounds. A recent work proposed extending MQTT with real-time services, taking advantage of Software Defined Networking (SDN) to manage the network resource. These extensions allow applications to specify real-time requirements that are then captured by a resource manager and used to reserve the necessary resources at the network layer. This paper shows that such MQTT extended architecture is analyzable from a worst-case timing perspective. We derive a system model that captures the real-time features and we present a response-time analysis to assess the schedulability of the real-time traffic. Finally, we validate the analysis with a set of experimental results
System-level scheduling of mixed-criticality traffics in avionics networks
ABSTRACT: System-level mixed-criticality design aims at reducing production cost and enhancing resource efficiency. This paper studies the technology of integrating mixed-criticality avionics traffics for Avionics Full-Duplex Switched Ethernet (AFDX) network, which can transmit both critical and non-critical traffics. These two traffics have different QoS requirements, such as low latency for critical traffics and high bandwidth for non-critical traffics. We use system-level compositional scheduling to integrate mixed-criticality traffics into one network to enhance the scalability of AFDX network. In the architecture of the proposed compositional scheduling, critical traffics are scheduled by bandwidth allocation gap-based scheduler, and non-critical traffics by Round Robin manner. To estimate the delay bound meeting requirements of applications, end-to-end delay for both critical and non-critical traffics are analyzed by using network calculus. Finally, a true time-based simulation of AFDX networks is conducted to verify the effectiveness of the proposed approach
Development of real-time and mixed criticality distributed systems through the DDS standard
El uso de middleware de distribución facilita la programación de sistemas distribuidos de tiempo real heterogéneos, y por extensión también puede facilitar la generación automática de código como parte de una estrategia de desarrollo basada en modelos. Sin embargo, esta clase de middleware presenta una complejidad añadida que dificulta su uso en sistemas con ciertos requisitos de criticidad o de tiempo real. En este trabajo se hace una revisión de algunos estudios previos en los que se muestra la posibilidad de utilizar un middleware de distribución centrado en los datos (DDS, Data Distribution Service) para la integración de aplicaciones con criticidad mixta en sistemas distribuidos.The use of distribution middleware facilitates the programming of heterogeneous real-time distributed systems, and it can also facilitate the automatic generation of source code when integrated as a part of a general MDE (Model-Driven Engineering) strategy. However, the complexity usually associated with distribution middleware puts a burden on the development of applications with hard real-time requirements or high levels of criticality. This paper gathers a set of previous works to present an overview on how a data-centric distribution middleware (DDS, Data Distribution Service) could be used in distributed applications with mixed criticality and real-time requirements. © 2018 Elsevier Doyma. All rights reserved.Este trabajo ha sido financiado en parte por el Gobierno de España en el proyecto TIN2014-56158-C4-2-P (M2C2)
Schedulability analysis and optimization of time-partitioned distributed real-time systems
RESUMEN: La creciente complejidad de los sistemas de control modernos lleva a muchas empresas a tener que re-dimensionar o re-diseñar sus soluciones para adecuarlas a nuevas funcionalidades y requisitos. Un caso paradigmático de esta situación se ha dado en el sector ferroviario, donde la implementación de las aplicaciones de señalización se ha llevado a cabo empleando técnicas tradicionales que, si bien ahora mismo cumplen con los requisitos básicos, su rendimiento temporal y escalabilidad funcional son sustancialmente mejorables. A partir de las soluciones propuestas en esta tesis, además de contribuir a la validación de sistemas que requieren certificación de seguridad funcional, también se creará la tecnología base de análisis de planificabilidad y optimización de sistemas de tiempo real distribuidos generales y también basados en particionado temporal, que podrá ser aplicada en distintos entornos en los que los sistemas ciberfísicos juegan un rol clave, por ejemplo en aplicaciones de Industria 4.0, en los que pueden presentarse problemas similares en el futuro.ABSTRACT:he increasing complexity of modern control systems leads many companies to have to resize or redesign their solutions to adapt them to new functionalities and requirements. A paradigmatic case of this situation has occurred in the railway sector, where the implementation of signaling applications has been carried out using traditional techniques that, although they currently meet the basic requirements, their time performance and functional scalability can be substantially improved. From the solutions proposed in this thesis, besides contributing to the assessment of systems that require functional safety certification, the base technology for schedulability analysis and optimization of general as well as time-partitioned distributed real-time systems will be derived, which can be applied in different environments where cyber-physical systems play a key role, for example in Industry 4.0 applications, where similar problems may arise in the future
A review on optimization techniques for the deployment and scheduling of distributed real-time systems
RESUMEN: En las ultimas tres décadas, se ha realizado un gran número de propuestas sobre la optimización del despliegue y planificación de sistemas de tiempo real distribuidos bajo diferentes enfoques algorítmicos que aportan soluciones aceptables a este problema catalogado como NP-difícil. En la actualidad, la mayor parte de los sistemas utilizados en el sector industrial son sistemas de criticidad mixta en los que se puede usar la planificación cíclica, las prioridades fijas y el particionado, que proporciona aislamiento temporal y espacial a las aplicaciones. Así, en este artículo se realiza una revisión de los trabajos publicados sobre este tema y se presenta un análisis de las diferentes soluciones aportadas para sistemas de tiempo real distribuidos basados en las políticas de planificación que se están usando en la práctica. Como resultado de la comparación, se presenta una tabla a modo de guía en la que se relacionan los trabajos revisados y se caracterizan sus soluciones.ABSTRACT: In the last three decades, a large number of proposals has been carried out for the optimization of the deployment and scheduling of distributed real-time systems under different algorithmic approaches that provide acceptable solutions for this NP-hard problem. Nowadays, most of the systems used in industry are mixed-criticallity systems which use cyclic scheduling, fixed-priority scheduling and partitioning, which provides both temporal and spatial isolation in the execution of applications. Thus, in this work a review of the works published on this topic is performed, as well as an analysis of the different proposed solutions for distributed real-time systems based on the scheduling policies that are used in practice. As a result of the comparison, a table intended as a guide is elaborated in which all the reviewed works are reported and their solutions are characterized.Este trabajo ha sido financiado en parte por el Gobierno de España y los fondos FEDER (AEI /FEDER, UE) en el proyecto TIN2017-86520-C3-3-R (PRECON-I4)