An Integrated Framework for Multiprocessor, Multimoded Real-Time Applications

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-30598-6_2In this paper we propose an approach for building real-time systems under a combination of requirements: specification and handling of operating modes and mode changes; implementation on top of a multiprocessor platform; integration of both aspects within a common framework; and connection with schedulability analysis procedures. The proposed approach uses finite state machines to describe operating modes and transitions, and a framework of real-time utilities that implements the required behaviour in Ada 2012. Automatic code generation plays an important role: the system is derived from the functional and timing specification, and implemented according to the abstractions provided by the framework. Response time analysis enables assessing the schedulability of the different operating modes and the transitions between modes.This work was partially supported by the Vicerrectorado de Investigación of the UPV (PAID-06-10-2397), Ministerio de Ciencia e Innovación (TIN2011-28567-C03- 03) and European Union (FP7-ICT-287702)Sáez Barona, S.; Real Sáez, JV.; Crespo, A. (2012). An Integrated Framework for Multiprocessor, Multimoded Real-Time Applications. En Reliable Software Technologies – Ada-Europe 2012. Springer. 18-34. https://doi.org/10.1007/978-3-642-30598-6_21834Wellings, A.J., Burns, A.: A Framework for Real-Time Utilities for Ada 2005. Ada Letters XXVII(2) (August 2007)Real, J., Crespo, A.: Incorporating Operating Modes to an Ada Real-Time Framework. Ada Letters 30(1) (April 2010)Sáez, S., Terrasa, S., Crespo, A.: A Real-Time Framework for Multiprocessor Platforms Using Ada 2012. In: Romanovsky, A., Vardanega, T. (eds.) Ada-Europe 2011. LNCS, vol. 6652, pp. 46–60. Springer, Heidelberg (2011)Joseph, M., Pandya, P.: Finding response times in a real-time system. British Computer Society Computer Journal 29(5), 390–395 (1986)Audsley, N., Burns, A., Richardson, M., Tindell, K., Wellings, A.J.: Applying new scheduling theory to static priority pre-emptive scheduling. Software Engineering Journal 8(5), 284–292 (1993)Real, J., Crespo, A.: Mode Change Protocols for Real-Time Systems: A Survey and a new Proposal. Real-Time Systems 26(2), 161–197 (2004)Harel, D.: Statecharts: A visual formalism for complex systems. The Science of Computer Programming 8(3), 231–274 (1987)Object Management Group: Unified Modeling Language (OMG UML) V2.4 (August 2011), http://www.omg.org/spec/UML/2.4.1Sáez, S., Terrasa, S., Lorente, V., Crespo, A.: Implementing Reactive Systems with UML State Machines and Ada 2005. In: Kordon, F., Kermarrec, Y. (eds.) Ada-Europe 2009. LNCS, vol. 5570, pp. 149–163. Springer, Heidelberg (2009)Burns, A., Wellings, A.J.: Dispatching Domains for Multiprocessor Platforms and their Representation in Ada. In: Real, J., Vardanega, T. (eds.) Ada-Europe 2010. LNCS, vol. 6106, pp. 41–53. Springer, Heidelberg (2010)Barnett, J.: State Chart XML (SCXML): State Machine Notation for Control Abstraction (May 2008), http://www.w3.org/TR/scxml

Combined Scheduling of Time-Triggered Plans and Priority Scheduled Task Sets

© Owner/Author (2016). This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in ACM SIGAda Ada Letters, 36(1), 68-76, http://dx.doi.org/10.1145/10.1145/2971571.2971580.[EN] Preemptive, priority-based scheduling on the one hand, and time-triggered scheduling on the other, are the two major techniques in use for development of real-time and embedded software. Both have their advantages and drawbacks with respect to the other, and are commonly adopted in mutual exclusion. In a previous paper, we proposed a software architecture that enables the combined and controlled execution of time-triggered plans and priority-scheduled tasks. The goal was to take advantage of the best of both approaches by providing deterministic, jitter-controlled execution of time-triggered tasks (e.g., control tasks), coexisting with a set of priority-scheduled tasks, with less demanding jitter requirements. In this paper, we briefly describe the approach, in which the time-triggered plan is executed at the highest priority level, controlled by scheduling decisions taken only at particular points in time, signalled by recurrent timing events. The rest of priority levels are used by a set of concurrent tasks scheduled by static or dynamic priorities. We also discuss several open issues such as schedulability analysis, use of the approach in multiprocessor architectures, usability in mixed-criticality systems and needed changes to make this approach Ravenscar compliant.This work has been partly supported by the Spanish Government’s project M2C2 (TIN2014-56158-C4-1-P-AR) and the European Commission’s project EMC2 (ARTEMIS-JU Call 2013 AIPP-5, Contract 621429).Real Sáez, JV.; Sáez Barona, S.; Crespo Lorente, A. (2016). Combined Scheduling of Time-Triggered Plans and Priority Scheduled Task Sets. Ada Letters. 36(1):68-76. https://doi.org/10.1145/2971571.2971580S6876361T. P. Baker and A. Shaw. The cyclic executive model and Ada. In Proceedings IEEE Real Time Systems Symposium 1988, Huntsville, Alabama, pages 120--129, 1988.P. Balbastre, I. Ripoll, J. Vidal, and A. Crespo. A Task Model to Reduce Control Delays. Real-Time Systems, 27(3):215--236, September 2004.A. Burns and R. Davis. Mixed Criticality Systems - A Review. Technical report, Depatment of Computer Science, University of York, 2013.A. Cervin. Integrated Control and Real-Time Scheduling. PhD thesis, Lund Institute of Technology, April 2003.R. Dobrin. Combining Offline Schedule Construction and Fixed Priority Scheduling in Real-Time Computer Systems. PhD thesis, Mälardalen University, 2005.S. Hong, X. Hu, and M. Lemmon. Reducing Delay Jitter of Real-Time Control Tasks through Adaptive Deadline Adjustments. In IEEE Computer Society, editor, 22nd Euromicro Conference on Real-Time Systems -- ECRTS, pages 229--238, 2010.J. W. S. Liu. Real-Time Systems. Prentice-Hall Inc., 2000.J. Palencia and M. González-Harbour. Schedulability Analysis for Tasks with Static and Dynamic Offsets. In 9th IEEE Real-Time Systems Symposium, 1998.M. J. Pont. The Engineering of Reliable Embedded Systems: LPC1769 edition. Number ISBN: 978-0-9930355-0-0. SafeTTy Systems Limited, 2014.J. Real and A. Crespo. Incorporating Operating Modes to an Ada Real-Time Framework. Ada Letters, 30(1):73--85, April 2010.J. Real, S. Sáez, and A. Crespo. Combining time-triggered plans with priority scheduled task sets. In M. Bertogna and L. M. Pinho, editors, Reliable Software Technologies -- Ada-Europe 2016, volume 9695 of Lecture Notes in Computer Science. Springer, June 2016.S. Sáez, J. Real, and A. Crespo. An integrated framework for multiprocessor, multimoded real-time applications. In M. Brorsson and L. Pinho, editors, Reliable Software Technologies -- Ada-Europe 2012, volume 7308, pages 18--34. Springer-Verlag, June 2012.S. Sáez, J. Real, and A. Crespo. Implementation of Timing-Event Anities in Ada/Linux. Ada Letters, 35(1), April 2015.A. J. Wellings and A. Burns. A Framework for Real-Time Utilities for Ada 2005. Ada Letters, XXVII(2), August 2007