DoRiS: Um Novo Protocolo de Comunicação de Tempo Real sobre Ethernet e sua Implementação em Linux/Xenomai
Resumo
Um novo protocolo de comunicação para sistemas de tempo real sobre Ethernet, chamado DoRiS, é descrito. Sua implementação foi realizada no sistema operacional Linux/Xenomai, a fim de torná-lo adequado aos sistemas de tempo real híbridos, compostos de serviços de tempo real críticos e não-críticos. Baseado num controle de acesso distribuído, o protocolo fornece previsibilidade temporal, confiabilidade e tolerância a falhas. Além disso, DoRiS provê uso eficiente da largura de banda, característica importante aos serviços que precisam de altas taxas de transmissão. Recentemente, o protocolo foi especificado formalmente e sua correção foi atestada através do uso de verificadores de modelos. O presente artigo aborda sua implementação. Resultados experimentais indicam seu bom desempenho quando comparado ao suporte atualmente oferecido pelo sistema Linux/Xenomai.Referências
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Pedreiras, P., Almeida, L., and Gai, P. (2002). “The FTT-Ethernet Protocol: Merging Flexibility, Timeliness and Efficiency”. In 14th Euromicro Conf. on Real-Time Systems, pages 134–142.
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Regnier, P., Lima, G., and Andrade, A. (2008a). “A TLA+ Formal Specification and Verification of a New Real-time Communication Protocol”. In Brazilian Symposium on Formal Methods, pages 209–224.
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Venkatrami, C. and Chiueh, T. (1994). “Supporting Real-Time Traffic on Ethernet”. In 15th IEEE Real-Time Systems Symposium, pages 282–286.
Bovet, D. P. and Cesati, M. (2005). Understanding the Linux Kernel (3rd ed.). O’Reilly.
Brito, A., Brasileiro, F., Leite, C. E., and Buriti, A. C. (2004). “Comunicação Ethernet em Tempo-real para uma Rede de Microcontroladores”. In XV Congresso Brasileiro de Automática.
Carreiro, F. B., Fonseca, J. A., and Pedreiras, P. (2003). “Virtual Token-Passing Ethernet - VTPE”. In 5th Int. Conf. on Fieldbus Systems and their Applications.
Cristian, F. (1988). “Agreeing on Who Is Present and Who Is Absent in a Synchronous Distributed System”. In 18th IEEE Int. Conf. on Fault-Tolerant Computing.
Decotignie, J.-D. (2005). “Ethernet-Based Real-Time and Industrial Communications”. IEEE (Special Issue on Industrial Communication Systems), 93(6):1102–1117.
Dolejs, O., Smolik, P., and Hanzalek, Z. (2004). “On the Ethernet Use for Real-time Publish-subscribe Based Applications”. In 5th IEEE Int. Workshop on Factory Communication Systems, pages 39–44.
Gerum P. et al. (2009). “Xenomai”. [link].
Hanssen, F. T. Y. and Jansen, P. G. (2003). “Real-Time Communication Protocols: an Overview”. Technical Report TR-CTIT-03-49, University of Twente, The Netherlands.
Kiszka, J. (2005). “The Real-Time Driver Model and First Applications”. In 7th Real-Time Linux Workshop.
Kiszka, J., Wagner, B., Zhang, Y., and Broenink, J. (2005). “RTnet - A Flexible Hard Real-Time Networking Framework”. In 10th IEEE Int. Conf. on Emerging Technologies and Factory Automation, pages 19–22.
Kohn, N., Varchmin, J.-U., Steiner, J., and Goltz, U. (2004). “Universal Communication Architecture For High-Dynamic Robot Systems Using QNX”. In 8th Int. Control, Automation, Robotics and Vision Conf., pages 205–210.
Lian, F.-L., Moyne, J. R., and Tilbury, D. M. (2001). “Performance Evaluation of Control Networks: Ethernet, ControlNet and DeviceNet”. IEEE Control Systems Magazine, 21(1):66–83.
Liu, J. W. S. (2000). Real-Time Systems. Prentice-Hall.
Pedreiras, P., Almeida, L., and Gai, P. (2002). “The FTT-Ethernet Protocol: Merging Flexibility, Timeliness and Efficiency”. In 14th Euromicro Conf. on Real-Time Systems, pages 134–142.
Regnier, P. and Lima, G. (2006). “Deterministic Integration of Hard and Soft Real-Time Communication over Shared-Ethernet”. In 8th Workshop on Real Time Systems.
Regnier, P., Lima, G., and Andrade, A. (2008a). “A TLA+ Formal Specification and Verification of a New Real-time Communication Protocol”. In Brazilian Symposium on Formal Methods, pages 209–224.
Regnier, P., Lima, G., and Barreto, L. (2008b). “Evaluation of Interrupt Handling Timeliness in Real-time Linux Operating Systems”. ACM SIGOPS Operating Systems Review, 42(6):52–63.
Venkatrami, C. and Chiueh, T. (1994). “Supporting Real-Time Traffic on Ethernet”. In 15th IEEE Real-Time Systems Symposium, pages 282–286.
Publicado
20/07/2009
Como Citar
REGNIER, Paul D. E.; CARIANHA, Antônio M.; LIMA, George.
DoRiS: Um Novo Protocolo de Comunicação de Tempo Real sobre Ethernet e sua Implementação em Linux/Xenomai. In: WORKSHOP DE SISTEMAS OPERACIONAIS (WSO), 6. , 2009, Bento Gonçalves/RS.
Anais [...].
Porto Alegre: Sociedade Brasileira de Computação,
2009
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p. 2453-2464.
