Abstract

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publicationCitation for published version (APA): Gheorghita, S. V., Palkovic, M., Hamers, J., Vandecappelle, A., Mamagkakis, S., Basten, T., ... Bosschere, . System scenario based design of dynamic embedded systems. (ES reports; Vol. 2007-06). Eindhoven: Technische Universiteit Eindhoven. General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. In the past decade, real-time embedded systems have become much more complex due to the introduction of a lot of new functionality in one application, and due to running multiple applications concurrently. This increases the dynamic nature of today's applications and systems, and tightens the requirements for their constraints in terms of deadlines and energy consumption. State-of-theart design methodologies try to cope with these novel issues by identifying several most used cases and dealing with them separately, reducing the newly introduced complexity. This paper presents a generic and systematic design-time/run-time methodology for handling the dynamic nature of modern embedded systems, which can be utilized by existing design methodologies to increase their efficiency. It is based on the concept of system scenarios, which group system behaviors that are similar from a multi-dimensional cost perspective, such as resource requirements, delay, and energy consumption, in such a way that the system can be configured to exploit this cost similarity. At design-time, these scenarios are individually optimized. Mechanisms for predicting the current scenario at run-time and for switching between scenarios are ...

Modern embedded applications usually have real-time constraints and they are implemented using heterogeneous multiprocessor systems-on-chip. Dimensioning a system requires accurate estimations of the worst-case execution time (WCET). Overestimation leads to over-dimensioning. This paper introduces a method for automatic discovery of scenarios that incorporate correlations between different parts of applications. It is based on the application parameters with a large impact on the execution time. We show on a benchmark that, using scenarios, the estimated WCET may be reduced with 16%.

Abstract. Modern multimedia applications usually have real-time constraints and they are implemented using application-domain specific embedded processors. Dimensioning a system requires accurate estimations of resources needed by the applications. Overestimation leads to over-dimensioning. For a good resource estimation, all the cases in which an application can run must be considered. To avoid an explosion in the number of different cases, those that are similar with respect to required resources are combined into, so called application scenarios. This paper presents a methodology and a tool that can automatically detect the most important variables from an application and use them to select and dynamically predict scenarios, with respect to the necessary time budget, for soft real-time multimedia applications. The tool was tested for three multimedia applications. Using a proactive scenario-based dynamic voltage scheduler based on the scenarios and the runtime predictor generated by our tool, the energy consumption decreases with up to 19%, while guaranteeing a frame deadline miss ratio close to zero.

Modern embedded applications usually have real-time constraints and they have requirements for low energy consumption. At system level, intra-task dynamic voltage scaling (DVS) is one of the most effective techniques for energy reduction. It changes the processor's supply voltage and clock frequency to the lowest level that still allows the real-time constraints to be met. In this paper, we present how intra-task scenarios, which capture correlations between different parts of the application, can be applied on top of existing DVS techniques, making them more effective. Furthermore, we extend our method for automatic discovery of scenarios and adapt it to the DVS requirements. We show that, by augmenting an existing DVS method with scenarios, the average energy consumption of two real-life benchmarks is reduced with 14% to 52%.