Performance analysis plays an increasingly important role in the design of embedded real-time systems. Time-to-market pressure in this domain is high while the available implementation technology is often pushed to its limit to minimize cost. This requires analysis of performance as early as possible in the life cycle. Simulation-based techniques are often not sufficiently productive. We present an alternative, analytical, approach based on Real-Time Calculus. Modular performance analysis is presented through a case study in which several candidate architectures are evaluated for a distributed in-car radio navigation system. The analysis is efficient due to the high abstraction level of the This work has been carried out as part of the boderc project under the responsibility of the Embedded Systems Institute.

The central idea behind interface-based design is to describe components by a component interface. In contrast to a component description that describes what a component does, a component interface describes how a component can be used. A well designed component interface provides enough information to decide whether two or more components can work together properly in a system. In this work, we expand the idea of interface-based design to the area of real-time system design. Here, the term of 'working together properly' refers to questions like: Does the composed system satisfy all requested real-time properties such as delay and throughput constraints? For this, we introduce Real-Time Interfaces, that connect the principles of Real-Time Calculus with Interface-based Design. In contrast to traditional real-time system design, in interface-based real-time system design the compliance to real-time constraints is checked at composition time. This leads to faster design processes and partly removes the need for the classical binary search approach to find an economically dimensioned system. Further, interface-based real-time system design also benefits from the properties of incremental design and independent implementability.

Recently, a number of frameworks were proposed to extend interface theory to the domains of single-processor and distributed real-time systems. This paper unifies some of these approaches and proves properties like refinement and independent implementability. We also explicitly state the requirements to a framework for these properties to be fulfilled. Further, a new notion of adaptive interfaces is introduced that supports the design by providing mechanisms for propagating system constraints, such as (end-to-end) delays, available computing and communication resources, buffer spaces, and energy. Guarantees and assumptions on interfaces are not any longer static but adapt according to the system environment. This can be used to answer synthesis questions at design time or to adapt system parameters to changing environment requirements at run-time. The applicability of the presented framework is proven by adapting it to a number of different real-time analysis models.

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