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  • 1.
    Ermedahl, Andreas
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Fredriksson, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Gustafsson, Jan
    Mälardalen University, School of Innovation, Design and Engineering.
    Altenbernd, Peter
    Mälardalen University, School of Innovation, Design and Engineering.
    Deriving the Worst-Case Execution Time Input Values2009In: 21st Euromicro Conference of Real-Time Systems, (ECRTS'09), Dublin, Ireland, 2009, p. 45-54Conference paper (Refereed)
    Abstract [en]

    A Worst-Case Execution Time (WCET) analysis derives upper bounds for execution times of programs. Such bounds are crucial when designing and verifying real-time systems. A major problem with today's WCET analysis approaches is that there is no feedback on the particular values of the input variables that cause the program's WCET. However, this is important information for the real-time system developer. We present a novel approach to overcome this problem. In particular, we present a method, based on a combination of input-sensitive static WCET analysis and systematic search over the value space of the input variables, to derive the input value combination that causes the WCET. We also present several different approaches to speed up the search. Our evaluations show that the WCET input values can be relatively quickly derived for many type of programs, even for program with large input value spaces. We also show that the WCET estimates derived using the WCET input values often are much tighter than the WCET estimates derived when all possible input value combinations are taken into account.

  • 2.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Accurate predictions of real-time properties for components2006Conference paper (Refereed)
  • 3.
    Fredriksson, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Improving predictability and resource utilization in component-based embedded real-time systems2008Doctoral thesis, monograph (Other academic)
  • 4.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Increasing Accuracy of Property Predictions for Embedded Real-Time Components2006Conference paper (Refereed)
    Abstract [en]

    Many embedded systems for vehicles and consumer electronics critically depend on efficient, reliable control software, and practical methods for their production. Component-based software engineering for embedded systems is currently gaining ground since variability, reusability, and maintainability are supported. However, existing tools and methods do not guarantee efficient resource usage in these systems. We present methods that increases the accuracy in extra-functional property predictions, by considering context without restricting reusability; thus, enabling less pessimistic extra-functional component properties and, hence, improving resource utilisation.

  • 5.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Transformation of component models to real-time models2005Licentiate thesis, monograph (Other scientific)
    Abstract [en]

    Industry is constantly looking for new developments in software for use in increasingly complex computer applications. Today, the development of component-based systems is an attractive area for both Industry and Academia. The systems we focus on in this thesis are embedded computers, in particular those in automotive systems. A modern car incorporates several embedded computers that control different functions of the car, e.g., anti-spin and anti-lock breaks. The main purpose of this thesis is to investigate how component technologies for use in embedded systems can reduce resource usage without compromising non-functional requirements, such as timeliness. The component-technologies available have not yet been used extensively in the vehicular domain. To understand why this is the case we have conducted a survey and performed evaluations of the requirements of the vehicular industry with respect to software and software development. The purpose of the evaluation was to provide a foundation for defining models, methods and tools for component-based software engineering. The main contribution of this work is the implementation and evaluation of a framework for resource-efficient mappings between component-models and real-time systems. Few component technologies today consider the mapping between components and run-time tasks. We show how effective mappings can reduce memory usage and CPU-overhead. The implemented framework utilizes genetic algorithms to find feasible, resource efficient mappings. We show how component-models designed for resource constrained safety-critical embedded real-time systems can use powerful compile-time techniques to realize the component-based approach and ensure predictable behaviour. Further, we propose a resource reclaiming strategy for component-based real-time systems, to decrease the impact of pessimistic execution time predictions. In our approach, components run in different quality levels as unused processor time is accumulated.

  • 6.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Land, Rikard
    Mälardalen University, Department of Computer Science and Electronics.
    Packaging Component-Analysis for Reuse2007Conference paper (Refereed)
    Abstract [en]

    Component-Based Software Engineering (CBSE) promises an improved ability to reuse software which would potentially decrease the development time while also improving the quality of the system, since the components are (re-)used by many. However, CBSE has not been as successful in the embedded systems domain as in the desktop domain, partly because requirements on embedded systems are stricter (e.g. requirements on safety, real-time and minimizing hardware resources). Moreover these requirements differ between industrial domains. Paradoxically, components should be context-unaware to be reusable at the same time as they should be context sensitive in order to be predictable and resource efficient. This seems to be a fundamental problem to overcome before the CBSE paradigm will be successful also in the embedded systems domain. Another problem is that some of the stricter requirements for embedded systems require certain analyses to be made, which may be very complicated and time-consuming for the system developer.

    This paper describes how one particular kind of analysis, of worst-case execution time, would fit into the CBSE development processes so that the component developer performs some analyses and presents the results in a form that is easily used for component and system verification during system development. This process model is not restricted to worst-case execution time analysis, but we believe other types of analyses could be performed in a similar way.

  • 7.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics. CC Systems, Västerås, Sweden.
    Land, Rikard
    Mälardalen University, Department of Computer Science and Electronics.
    Reusable Component Analysis for Component-Based Embedded Real-Time Systems2007In: Proceedings of the International Conference on Information Technology Interfaces, ITI, 2007, 2007, p. 615-620Conference paper (Refereed)
    Abstract [en]

    Component-Based Software Engineering (CBSE) promises an improved ability to reuse software which would potentially decrease the development time while also improving the quality of the system, since the components are (re-)used by many. However, CBSE has not been as successful in the embedded systems domain as in the desktop domain, partly because requirements on embedded systems are stricter (e.g. requirements on safety, real-time and minimizing hardware resources). Moreover these requirements differ between industrial domains. Paradoxically, components should be context-unaware to be reusable at the same time as they should be context sensitive in order to be predictable and resource efficient. This seems to be a fundamental problem to overcome before the CBSE paradigm will be successful also in the embedded systems domain. Another problem is that some of the stricter requirements for embedded systems require certain analyses to be made, which may be very complicated and time-consuming for the system developer.

    This paper describes how one particular kind of analysis, of worst-case execution time, would fit into the CBSE development processes so that the component developer performs some analyses and presents the results in a form that is easily used for component and system verification during system development. This process model is not restricted to worst-case execution time analysis, but we believe other types of analyses could be performed in a similar way.

  • 8.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Nolin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Clustering Worst-Case Execution Times for Software Components2007In: Proceedings of the 7th International Workshop on Worst Case Execution Time Analysis (WCET'07), Pisa, Italy, 2007, p. 19-25Conference paper (Refereed)
    Abstract [en]

    For component-based systems, classical techniques for WCET-estimation produce unacceptable overestimations of the WCET. This is because software components have more general behavior in order to support reuse. Existing tools and methods for component-based software engineering (CBSE) do not yet adequately consider reusable analyses.

    We present a method that allows different WCETs to be associated with subsets of the component behavior by clustering WCETs with respect to behavior. The method is intended to be used for facilitating reusable WCET analysis for reusable software components. We illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for components with rich behavior.

  • 9.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Contract-Based Reusable Analysis for Software Components with Extra-Functional Properties2007In: Proceedings of the Work-In-Progress (WIP) session of the 19th Euromicro Conference on Real-Time Systems (ECRTS'07), Pisa, Italy, 2007, p. 57-60Conference paper (Refereed)
    Abstract [en]

    Component-based software engineering (CBSE) for embedded systems is currently gaining ground because of shortened time-to-market, reduced development costs and increased software quality. One main characteristic of CBSE that enable these benefits is its facilitation of component reuse. However, existing tools and methods do not consider reuse of extra-functional properties in these systems.

    In this paper we extend our previous work on contract-based reusable execution time predictions for software components with additional extra-functional properties, such as memory and energy consumption.

  • 10.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Ermedahl, Andreas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Worst-Case Execution Time Clustering for Software Components2007Report (Other academic)
    Abstract [en]

    For component-based systems, classical techniques for WCET-estimation produce unacceptable overestimations of the WCET. This is because software components have more general behavior in order to support reuse. Existing tools and methods for component-based software engineering (CBSE) do not yet adequately consider reusable analyses. We present a method that allows different WCETs to be associated with subsets of the component behavior by clustering WCETs with respect to behavior. The method is intended to be used for facilitating reusable WCET analysis for reusable software components. We illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for components with rich behavior.

  • 11.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Schmidt, Heinz
    Mälardalen University, Department of Computer Science and Electronics.
    Contract-Based Reusable Worst-Case Execution Time Estimate2007In: Proceedings of the 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA'07),, 2007, p. 39-46Conference paper (Refereed)
    Abstract [en]

    We present a contract-based technique to achieve reuse of known worst-case execution times (WCET) in conjunction with reuse of software components. For resource constrained systems, or systems where high degree of predictability is needed, classical techniques for WCET-estimation will result in unacceptable overestimation of the execution-time of reusable software components with rich behavior. Our technique allows different WCETs to be associated with subsets of the component behavior. The appropriate WCET for any usage context of the component is selected be means of component contracts over the input domain. In a case-study we illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for reusable components with rich behavior.

  • 12.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Schmidt, Heinz
    Mälardalen University, Department of Computer Science and Electronics.
    Predicting Execution-Time for Variable Behaviour Embedded Real-Time Components2006In: Workshop on Models and Analysis for Automotive Systems (WMAAS'06) in conjunction with the 27th IEEE Real-Time Systems Symposium (RTSS'06), Rio de Janeiro, Brazil, 2006Conference paper (Refereed)
  • 13.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Schmidt, Heinz
    Mälardalen University, Department of Computer Science and Electronics.
    Reusing Worst-Case Execution Time Analysis with Component Contracts2007In: Proceedings of the 9th Real-Time in Sweden (RTiS'07), 2007Conference paper (Refereed)
    Abstract [en]

    We present a contract-based technique to achieve reuse of known worst-case execution times (WCET) in conjunction with reuse of software components. For resource constrained systems, or systems where high degree of predictability is needed, classical techniques for WCET-estimation will result in unacceptable overestimation of the execution-time of reusable software components with rich behavior. Our technique allows different WCETs to be associated with subsets of the component behavior. The appropriate WCET for any usage context of the component is selected be means of component contracts over the input domain. In a case-study we illustrate our technique and demonstrate its potential in achieving tight WCET-estimates for reusable components with rich behavior.

  • 14.
    Fredriksson, Johan
    et al.
    Mälardalen University, Department of Computer Science and Engineering.
    Sandström, Kristian
    Mälardalen University, Department of Computer Science and Engineering.
    Åkerholm, Mikael
    Mälardalen University, Department of Computer Science and Engineering.
    Optimizing Resource Usage in Component-Based Real-Time Systems2005In: Component-Based Software Engineering: 8th International Symposium, CBSE 2005, St. Louis, MO, USA, May 14-15, 2005. Proceedings, Springer, 2005, p. 49-65Chapter in book (Refereed)
    Abstract [en]

    The embedded systems domain represents a class of systems that have high requirements on cost efficiency as well as run-time properties such as timeliness and dependability. The research on component-based systems has produced component technologies for guaranteeing real-time properties. However, the issue of saving resources by allocating several components to real-time tasks has gained little focus. Trade-offs when allocating components to tasks are, e.g., CPU-overhead, footprint and integrity. In this paper we present a general approach for allocating components to real-time tasks, while utilizing existing real-time analysis to ensure a feasible allocation. We demonstrate that CPU-overhead and memory consumption can be reduced by as much as 48% and 32% respectively for industrially representative systems.

  • 15.
    Möller, Anders
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Åkerholm, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Mikael, Nolin
    Mälardalen University, Department of Computer Science and Electronics.
    Evaluation of Component Technologies with Respect to Industrial Requirements2004In: Conference Proceedings of the EUROMICRO, 2004, p. 56-63Conference paper (Other academic)
    Abstract [en]

    We compare existing component technologies for embedded systems with respect to industrial requirements. The requirements are collected from the vehicular industry, but our findings are applicable to similar industries developing resource constrained safety critical embedded distributed real-time computer systems. One of our conclusions is that none of the studied technologies is a perfect match for the industrial requirements. Furthermore, no single technology stands out as being a significantly better choice than the others; each technology has its own pros and cons. The results of our evaluation can be used to guide modifications or extensions to existing technologies, making them better suited for industrial deployment. Companies that want to make use of component-based software engineering as available today can use this evaluation to select a suitable technology.

  • 16.
    Möller, Anders
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Åkerholm, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Fröberg, Joakim
    Mälardalen University, Department of Computer Science and Electronics.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Industrial Requirements on Component Technologies for Vehicular Control Systems2006Report (Other academic)
    Abstract [en]

    Software component technologies for automotive applications are desired due to the envisioned benefits in reuse, variant handling, and porting; thus, facilitating both efficient development and increased quality of software products. Component based software development has had success in the PC application domain, but requirements are different in the embedded domain and existing technologies does not match. Hence, software component technologies have not yet been generally accepted by embedded-systems industries.

    In order to better understand why this is the case, we present two separate case-studies together with an evaluation of the existing component technologies suitable for embedded control systems.

    The first case-study presents a set of requirements based on industrial needs, which are deemed decisive for introducing a component technology. Furthermore, in the second study, we asked the companies involved to grade these requirements.

    Then, we use these requirements to compare existing component technologies suitable for embedded systems. One of our conclusions is that none of the studied technologies is a perfect match for the industrial requirements. Furthermore, no single technology stands out as being a significantly better choice than the others; each technology has its own pros and cons.

    The results can be used to guide modifications and/or extensions to existing component technologies in order to make them better suited for industrial deployment in the automotive domain. The results can also serve to guide other software engineering research by showing the most desired areas within component-based software engineering.

  • 17.
    Pavlova, Irena
    et al.
    Sofia University, Sofia, Bulgaria.
    Åkerholm, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Application of Built-In-Testing in Component-Based Embedded Systems2006In: Proceedings of the ISSTA 2006 Workshop on Role of Software Architecture for Testing and Analysis, ROSATEA '06, 2006, p. 51-52Conference paper (Refereed)
    Abstract [en]

    This work-in-progress paper discusses challenges with application of Built-In Testing (BIT) in component-based embedded-systems. Testing constitutes a large part of the time and budget in development of embedded software systems. Such systems are often mission-critical, making testing highly important, and at the same time testing em-bedded systems is challenging because of their limited observability. We investigate the possible application of BIT in components for embedded systems, as a technique to advance the technology and knowledge for analysis and verification of functional correctness, real-time behavior, safety, and reliability of these systems.

  • 18.
    Åkerholm, Mikael
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Carlson, Jan
    Mälardalen University, Department of Computer Science and Electronics.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Hansson, Hans
    Mälardalen University, Department of Computer Science and Electronics.
    Håkansson, John
    Uppsala University, Sweden.
    Möller, Anders
    Mälardalen University, Department of Computer Science and Electronics.
    Pettersson, Paul
    Uppsala University, Sweden.
    Tivoli, Massimo
    University of L'Aquila, Italy.
    The SAVE approach to component-based development of vehicular systems2007In: Journal of Systems and Software, ISSN 0164-1212, E-ISSN 1873-1228, Vol. 80, no 5, p. 655-667Article in journal (Refereed)
    Abstract [en]

    The component-based strategy aims at managing complexity, shortening time-to-market, and reducing maintenance requirements by building systems with existing components. The full potential of this strategy has not yet been demonstrated for embedded software, mainly because of specific requirements in the domain, e.g., those related to timing, dependability, and resource consumption. We present SaveCCT - a component technology intended for vehicular systems, show the applicability of SaveCCT in the engineering process, and demonstrate its suitability for vehicular systems in an industrial case-study. Our experiments indicate that SaveCCT provides appropriate expressiveness, resource efficiency, analysis and verification support for component-based development of vehicular software. 

  • 19.
    Åkerholm, Mikael
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Carlson, Jan
    Mälardalen University, Department of Computer Science and Electronics.
    Fredriksson, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Hansson, Hans
    Mälardalen University, Department of Computer Science and Electronics.
    Sjödin, Mikael
    Mälardalen University, Department of Computer Science and Electronics.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Håkansson, John
    Mälardalen University, Department of Computer Science and Electronics.
    Pettersson, Paul
    Mälardalen University, Department of Computer Science and Electronics.
    Handling Subsystems using the SaveComp Component Technology2006In: Workshop on Models and Analysis for Automotive Systems (WMAAS'06) in conjunction with the 27th IEEE Real-Time Systems Symposium (RTSS'06), Rio de Janeiro, Brazil, 2006Conference paper (Refereed)
1 - 19 of 19
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