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

Mapping AADL models to a repository of multiple schedulability analysis techniques

To fill the gap between the modeling of real-time systems and the scheduling analysis, we propose a framework that supports seamlessly the two aspects: 1) modeling a system using a methodology, in our case study, the Architecture Analysis and Design Language (AADL), and 2) helping to easily check temporal requirements (schedulability analysis, worst-case response time, sensitivity analysis, etc.). We introduce an intermediate framework called MoSaRT, which supports a rich semantic concerning temporal analysis. We show with a case study how the input model is transformed into a MoSaRT model, and how our framework is able to generate the proper models as inputs to several classic temporal analysis tools

An Analytical Solution for Probabilistic Guarantees of Reservation Based Soft Real-Time Systems

We show a methodology for the computation of the probability of deadline miss for a periodic real-time task scheduled by a resource reservation algorithm. We propose a modelling technique for the system that reduces the computation of such a probability to that of the steady state probability of an infinite state Discrete Time Markov Chain with a periodic structure. This structure is exploited to develop an efficient numeric solution where different accuracy/computation time trade-offs can be obtained by operating on the granularity of the model. More importantly we offer a closed form conservative bound for the probability of a deadline miss. Our experiments reveal that the bound remains reasonably close to the experimental probability in one real-time application of practical interest. When this bound is used for the optimisation of the overall Quality of Service for a set of tasks sharing the CPU, it produces a good sub-optimal solution in a small amount of time.Comment: IEEE Transactions on Parallel and Distributed Systems, Volume:27, Issue: 3, March 201

Securing Real-Time Internet-of-Things

Modern embedded and cyber-physical systems are ubiquitous. A large number of critical cyber-physical systems have real-time requirements (e.g., avionics, automobiles, power grids, manufacturing systems, industrial control systems, etc.). Recent developments and new functionality requires real-time embedded devices to be connected to the Internet. This gives rise to the real-time Internet-of-things (RT-IoT) that promises a better user experience through stronger connectivity and efficient use of next-generation embedded devices. However RT- IoT are also increasingly becoming targets for cyber-attacks which is exacerbated by this increased connectivity. This paper gives an introduction to RT-IoT systems, an outlook of current approaches and possible research challenges towards secure RT- IoT frameworks

An optimal fixed-priority assignment algorithm for supporting fault-tolerant hard real-time systems

The main contribution of this paper is twofold. First, we present an appropriate schedulability analysis, based on response time analysis, for supporting fault-tolerant hard real-time systems. We consider systems that make use of error-recovery techniques to carry out fault tolerance. Second, we propose a new priority assignment algorithm which can be used, together with the schedulability analysis, to improve system fault resilience. These achievements come from the observation that traditional priority assignment policies may no longer be appropriate when faults are being considered. The proposed schedulability analysis takes into account the fact that the recoveries of tasks may be executed at higher priority levels. This characteristic is very important since, after an error, a task certainly has a shorter period of time to meet its deadline. The proposed priority assignment algorithm, which uses some properties of the analysis, is very efficient. We show that the method used to find out an appropriate priority assignment reduces the search space from O(n!) to O(n/sup 2/), where n is the number of task recovery procedures. Also, we show that the priority assignment algorithm is optimal in the sense that the fault resilience of task sets is maximized as for the proposed analysis. The effectiveness of the proposed approach is evaluated by simulation

New schedulability analysis for WiDom

WiDom is a wireless prioritized medium access control (MAC) protocol which offers a very large number of priority levels. Hence, it brings the potential for employing non-preemptive static-priority scheduling and schedulability analysis for a wireless channel assuming that the overhead of WiDom is modeled properly. One schedulability analysis for WiDom has already been proposed but recent research has created a new version of WiDom with lower overhead (we call it: WiDom with a master node) and for this version of WiDom no schedulability analysis exists. Also, common to the previously proposed schedulability analyses for WiDom is that they cannot analyze message streams with release jitter. Therefore, in this paper we propose a new schedulability analysis for WiDom (with a master node). We also extend the WiDom analyses (with and without master node) to work also for message streams with release jitter

How OEMs and Suppliers can face the Network Integration Challenges

International audienceSystems integration is a major challenge in many industries. Systematic analysis of the complex integration effects, especially with respect to timing and performance, significantly improves the design process, enables optimizations, and increases the quality and profit of a product. And it helps to improve supply-chain communications. This paper surveys a set of interesting experiments we have conducted on a real-world automotive communication network using our new SymTA/S schedulability analysis technology. We demonstrate that, and how, analysis technology helps answering key integration questions, thereby carefully respecting the established business models