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Embedded reactive real-time systems are ubiquitous today, and provide increasingly complex functionality for example in modern automotive, avionics or medical products. This rising complexity makes it important to apply high-level design approaches, which, however, traditionally make critical low-level aspects such as timing hard to control. This project will investigate investigates a novel, holistic approach for the design of timing-predictable, efficient reactive systems, which considers the modeling modelling and programming level as well as the execution platform.

A key contribution will be aim is to combine a formal semantical basis, which is provided by the synchronous model of computation and which results in predictable reactive control flow, with recent architectural developments that offer predictable timing at the instruction level. Compared to typical design approaches today, based on C-like languages and processors that optimize optimise the average case at the expense of predictability, this will the objective is to reduce timing uncertainties at the control-flow level as well as the architectural level. On the practical side the project will develop is developing a model-based design flow and tool chain for implementing timing-predictable, reactive systems, including a synchronous modeling modelling and programming language, a compiler, a timing analyzeranalyser, and a predictable execution platform derived from the Berkeley/Columbia PRET architecture.


Abstract. This is a journal extended version of the [DATE’13] publication which includes in addition: (i) a description of the mapping from the Sequentially Constructive (SC) language to the SC graph (SCG); (ii) detailed discussions on thread and statement reincarnation; (iii) a full section on the formalisation of SC based on free scheduling of SCGs; (iv) a more general SC Model of Computation based on the notion of confluence;  (v) a revised (positive) definition of SC-Admissibility; (vi) definition of valid SC-schedules; (vii) proof that every ASC schedulable program is indeed SC; (viii) detailed discussion on conservative approximations and (ix) additional examples for illustrating ineffective writes, failure despite deterministic outcome, data-dependency of SC and enforced determinism via reduction of admissible runs.


[RePP'14] Towards interactive timing analysis for designing reactive systems.

I. Fuhrmann, D. Broman, S. Smyth, and R. von Hanxleden.

Reconciling Performance and Predictability (RePP'14), satellite event of ETAPS'14, April 2014.

Abstract. Reactive systems are increasingly developed using high-level modeling tools. Such modeling tools may facilitate formal reasoning about concurrent programs, but provide little help when timing-related problems arise and deadlines are missed when running a real system. In these cases, the modeler has typically no information about timing properties and costly parts of the model; there is little or no guidance on how to improve the timing characteristics of the model. In this paper, we propose a design methodology where interactive timing analysis is an integral part of the modeling process. This methodology concerns how to aggregate timing values in a user-friendly manner and how to define timing analysis requests. We also introduce and formalize a new timing analysis interface that is designed for communicating timing information between a high-level modeling tool and a lower-level timing analysis tool.




[SYNCHRON’12] Sequentially Constructive Concurrency: A Conservative Extension of the Synchronous Model of Computation. (slides)