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  • 1.
    Bohlin, markus
    et al.
    SICS.
    Lu, Yue
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Kreuger, Per
    SICS, Sweden.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Best-Effort Simulation-Based Timing Analysis using Hill-Climbing with Random Restarts2009In: In Proc. of RTCSA, Aug. 2009., 2009Conference paper (Refereed)
  • 2.
    Bohlin, Markus
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Lu, Yue
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Kreuger, Per
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Simulation-Based Timing Analysis of Complex Real-Time Systems2009In: 2009 15TH IEEE INTERNATIONAL CONFERENCE ON EMBEDDED AND REAL-TIME COMPUTING SYSTEMS AND APPLICATIONS, PROCEEDINGS, 2009, p. 321-328Conference paper (Refereed)
    Abstract [en]

    This paper presents an efficient best-effort approach for simulation-based timing analysis of complex real- time systems. The method can handle in principle any software design that can be simulated, and is based on controlling simulation input using a simple yet novel hill- climbing algorithm. Unlike previous approaches, the new algorithm directly manipulates simulation parameters such as execution times, arrival jitter and input. An evaluation is presented using six different simulation models, and two other simulation methods as reference: Monte Carlo simulation and MABERA. The new method proposed in this paper was 4-11% more accurate while at the same time 42 times faster, on average, than the reference methods.

  • 3.
    Huselius, Joel
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Kraft, Johan
    Mälardalen University, Department of Computer Science and Electronics.
    Hansson, Hans
    Mälardalen University, Department of Computer Science and Electronics.
    Punnekkat, Sasikumar
    Mälardalen University, Department of Computer Science and Electronics.
    Evaluating the Quality of Models Extracted from Embedded Real-Time Software2007In: Proceedings of the International Symposium and Workshop on Engineering of Computer Based Systems, 2007, p. 577-585Conference paper (Refereed)
    Abstract [en]

    Due to the high cost of modeling, model-based techniques are yet to make their impact in the embedded systems industry, which still persist on maintaining code-oriented legacy systems. Re-engineering existing code-oriented systems to fit model-based development is a risky endeavor due to the cost and efforts required to maintain correspondence between the code and model. We aim to reduce the cost of modeling and model maintenance by automating the process, thus facilitating model-based techniques. We have previously proposed the use of automatic model extraction from recordings of existing embedded real-time systems. To estimate the quality of the extracted models of timing behavior, we need a framework for objective evaluation. In this paper, we present such a framework to empirically test and compare extracted models, and hence obtain an implicit evaluation of methods for automatic model extraction. We present a set of synthetic benchmarks to be used as test cases for emulating timing behaviors of diverse systems with varying architectural styles, and extract automatic models out of them. We discuss the difficulties in comparing response time distributions, and present an intuitive and novel approach along with associated algorithms for performing such a comparison. Using our empirical framework, and the comparison algorithms, one could objectively determine the correspondence between the model and the system being modeled.

  • 4.
    Kienle, Holger
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Müller, Hausi
    University of Victoria, Canada.
    Software Reverse Engineering in the Domain of Complex Embedded Systems2012In: Reverse Engineering, InTech, 2012Chapter in book (Other academic)
    Abstract [en]

    This chapter provides a review of reverse engineering of software for complex embedded systems. Our review is motivated by the observation that the reach and importance of embedded systems are growing along with their complexity. Thus, software reverse engineering can be expected to play a more prominent role in the evolution of large industrial embedded systems in the future. The chapter focuses on reverse engineering tools and techniques that are particularly suitable for complex embedded systems. These systems have unique characteristics and challenges compared to other domains. A key concern is the timing behavior of embedded systems, which is addressed by timing analysis. Consequently, we survey timing analysis techniques, assessing their applicability for complex embedded systems. The objective of this chapter is twofold: On the one hand, we aim to identify tools and techniques that are promising candidates for industrial application; on the other hand, we survey the current research landscape with the aim to identify opportunities for future research in software reverse engineering.

  • 5.
    Kienle, Holger
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    System-specific static code analyses: a case study in the complex embedded systems domain2012In: Software quality journal, ISSN 0963-9314, E-ISSN 1573-1367, Vol. 20, no 2, p. 337-367Article in journal (Refereed)
    Abstract [en]

    In this paper, we are exploring the approach to utilize system-specific static analyses of code with the goal to improve software quality forspecific software systems. Specialized analyses, tailored for a particular system, make it possible to take advantage of system/domainknowledge that is not available to more generic analyses. Furthermore, analyses can be selected and/or developed in order to best meet the challenges and specific issues of the system at hand. As a result, such analyses can be used as a complement to more generic code analysistools because they are likely to have a better impact on (business) concerns such as improving certain software quality attributes and reducing certain classes of failures. We present a case study of a large, industrial embedded system, giving examples of what kinds of analyses could be realized and demonstrate the feasibility of implementing such analyses. We synthesize lessons learned based on our case study and provide recommendations on how to realize system-specific analyses and how to get them adopted by industry.

  • 6.
    Kienle, Holger
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    System-specific Static Code Analyses for Complex Embedded Systems2010Conference paper (Refereed)
  • 7.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Enabling Timing Analysis of Complex Embedded Software Systems2010Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Cars, trains, trucks, telecom networks and industrial robots are examples of products relying on complex embedded software systems, running on embedded computers. Such systems may consist of millions of lines of program code developed by hundreds of engineers over many years, often decades.

    Over the long life-cycle of such systems, the main part of the product development costs is typically not the initial development, but the software maintenance, i.e., improvements and corrections of defects, over the years. Of the maintenance costs, a major cost is the verification of the system after changes has been applied, which often requires a huge amount of testing. However, today's techniques are not sufficient, as defects often are found post-release, by the customers. This area is therefore of high relevance for industry.

    Complex embedded systems often control machinery where timing is crucial for accuracy and safety. Such systems therefore have important requirements on timing, such as maximum response times. However, when maintaining complex embedded software systems, it is difficult to predict how changes may impact the system's run-time behavior and timing, e.g., response times.Analytical and formal methods for timing analysis exist, but are often hard to apply in practice on complex embedded systems, for several reasons. As a result, the industrial practice in deciding the suitability of a proposed change, with respect to its run-time impact, is to rely on the subjective judgment of experienced developers and architects. This is a risky and inefficient, trial-and-error approach, which may waste large amounts of person-hours on implementing unsuitable software designs, with potential timing- or performance problems. This can generally not be detected at all until late stages of testing, when the updated software system can be tested on system level, under realistic conditions. Even then, it is easy to miss such problems. If products are released containing software with latent timing errors, it may cause huge costs, such as car recalls, or even accidents. Even when such problems are found using testing, they necessitate design changes late in the development project, which cause delays and increases the costs.

    This thesis presents an approach for impact analysis with respect to run-time behavior such as timing and performance for complex embedded systems. The impact analysis is performed through optimizing simulation, where the simulation models are automatically generated from the system implementation. This approach allows for predicting the consequences of proposed designs, for new or modified features, by prototyping the change in the simulation model on a high level of abstraction, e.g., by increasing the execution time for a particular task. Thereby, designs leading to timing-, performance-, or resource usage problems can be identified early, before implementation, and a late redesigns are thereby avoided, which improves development efficiency and predictability, as well as software quality.

    The contributions presented in this thesis is within four areas related to simulation-based analysis of complex embedded systems: (1) simulation and simulation optimization techniques, (2) automated model extraction of simulation models from source code, (3) methods for validation of such simulation models and (4) run-time recording techniques for model extraction, impact analysis and model validation purposes. Several tools has been developed during this work, of which two are in commercialization in the spin-off company Percepio AB. Note that the Katana approach, in area (2), is subject for a recent patent application - patent pending.

     

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    FULLTEXT01
  • 8.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    RTSSim - A Simulation Framework for Complex Embedded Systems2009Report (Other academic)
    Abstract [en]

    This report presents the current state of RTSSim, a simulation framework for complex embedded systems focusing on timing and resource usage properties. The report presents the core concepts of RTSSim, the elements of RTSSim simulation models and associated operations, as well as an example of a fairly complex RTSSim simulation model.

  • 9.
    Kraft, Johan
    et al.
    Mälardalen University, Department of Computer Science and Electronics.
    Huselius, Joel
    Mälardalen University, Department of Computer Science and Electronics.
    Legacy Issues in Industrial Software Development2007Report (Other academic)
    Abstract [en]

    This report presents the results of the graduate course ”Legacy Issues in Industrial Software

    Development”, which was organized at Malardalen Real-Time Research Centre (MRTC) at

    Malardalen University during winter 2006-2007.

  • 10.
    Kraft, Johan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kienle, Holger
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Crnkovic, Ivica
    Mälardalen University, School of Innovation, Design and Engineering.
    Hansson, Hans
    Mälardalen University, School of Innovation, Design and Engineering.
    Software Maintenance Research in the PROGRESS Project for Predictable Embedded Software Systems2011In: 15th European Conference on Software Maintenance and Reengineering (CSMR'11) / [ed] Mens, T; Kanellopoulos, Y; Winter, A, Los Alamitos: IEEE Computer Society, 2011, p. 335-338Conference paper (Refereed)
    Abstract [en]

    PROGRESS is a project and strategic research centre at Malardalen University in Sweden that is funded for 2006-2010 by the Swedish Foundation for Strategic Research (SSF). PROGRESS research targets embedded software in the vehicular, automation, and telecom domains, focusing on the areas of component technology, verification and analysis for predictability, predictable execution, as well as reuse and maintenance of legacy embedded software. We first describe the funding, organization and research areas of PROGRESS, and then give several examples of PROGRESS research that addresses maintenance of legacy embedded software with the goal to improve program comprehension, quality assurance, and debugging. Specifically, we describe research in tracing and trace visualization, impact analysis of temporal behavior, slicing, and system-specific static analyses.

  • 11.
    Kraft, Johan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Lu, Yue
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Wall, Anders
    Mälardalen University, School of Innovation, Design and Engineering.
    A Metaheuristic Approach for Best Effort Timing Analysis targeting Complex Legacy Real-Time Systems2008In: PROCEEDINGS OF THE 14TH IEEE REAL-TIME AND EMBEDDED TECHNOLOGY AND APPLICATIONS SYMPOSIUM, 2008, p. 258-269Conference paper (Refereed)
    Abstract [en]

    Many companies developing real-time systems today have today no means for response time analysis, as their systems violate the assumptions of traditional analytical methods for response-time analysis and are too complex for exhaustive analysis using model checking.

    This paper presents a novel approach for best effort response time analysis targeting such systems, where probabilistic simulation is guided by a search algorithm of metaheuristic type, similar to genetic algorithms.

    The best effort approach means that the result is not guaranteed to be the worst-case response time, but also that the method scales to large industrial systems.

    The proposed method should be regarded as a form of testing, focusing on timing properties.

    An evaluation is presented which indicates that the proposed approach is significantly more efficient than traditional probabilistic simulation in finding extreme task response times. The paper also presents a method for finding good parameters for the search algorithm, in order to improve its efficiency.

  • 12.
    Kraft, Johan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Continuous Constant-Memory Monitoring of Embedded Software Timing2011In: 2nd International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems (WATERS'11), satellite workshop of EUROMICRO Conference on Real-Time Systems (ECRTS'11), 2011Conference paper (Refereed)
    Abstract [en]

    A method is presented for generating statistical models of timing data continuously over very long monitoring sessions. This method is intended for memory-efficient runtime modeling of timing properties in embedded software systems, such as execution times or inter-arrival times, but is a quite generic method that should be applicable for other purposes and domains as well. Specifically, we intend to use this method as a component in automatic generation of simulation models for probabilistic timing analysis of complex embedded software systems. Given a stream of data as input, this method gradually builds up a statistical model capturing the approximate distribution of the data. The method uses a modest and fixed amount of on-target RAM, decided by the desired accuracy of the model, and allows for long monitoring sessions covering billions of data points. The paper presents the motivation, algorithm, a prototype implementation and evaluation using real execution time data from an ARM7 microcontroller.

  • 13.
    Kraft, Johan
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Wall, Anders
    ABB.
    Kienle, Holger
    Mälardalen University, School of Innovation, Design and Engineering.
    Trace Recording for Embedded Systems: Lessons Learned from Five Industrial Projects2010In: Lecture Notes in Computer Science, vol. 6418, Springer, 2010, p. 315-329Chapter in book (Refereed)
    Abstract [en]

    This paper presents experiences from five industry collaboration projects performed between 2004 - 2009 where solutions for embedded systems trace recording have been developed and evaluated; in four cases for specific industrial systems and in the last case as a generic solution for a commercial real-time operating system, in collaboration with the RTOS company. The experiences includes technical solutions regarding efficient instrumentation and logging, technology transfer issues and evaluation results regarding CPU and RAM overhead. A brief overview of the Tracealyzer tool is also presented, a result of the first project (2004) which still is used by ABB Robotics and now in commercialization.

  • 14.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Bohlin, Markus
    Swedish Institute of Computer Science, Kista, Sweden).
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Kreuger, Per
    Swedish Institute of Computer Science, Kista, Sweden).
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Approximate Timing Analysis of Complex Legacy Real-Time Systems using Simulation Optimization2008In: Proceedings of the Work-In-Progress (WIP) track of the 29th IEEE Real-Time Systems Symposium (RTSS), Barcelona, Spain, 2008Conference paper (Refereed)
  • 15.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Cicchetti, Antonio
    Mälardalen University, School of Innovation, Design and Engineering.
    Bygde, Stefan
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Transformational Specification of Complex Legacy Real-Time Systems via Semantic Anchoring2009In: 2nd IEEE International Workshop on Component-Based Design of Resource-Constrained Systems (CORCS 2009) @ COMPSAC, 2009, p. 1183-1188Conference paper (Refereed)
    Abstract [en]

    RTSSim is a framework for simulating models extracted from complex legacy real-time systems which are task-oriented, run on a single processor and are developed in C. Such RTSSim models describe functional and temporal behavior as well as the resource usage of the system. However, the semantics specification of RTSSim models remains a challenging problem indeed, especially with tractable complexity to obtain a formal model which can be analyzed for instance by a model checking tool. In this paper, we present an approach towards using semantic anchoring for the transformational specification of RTSSim models, by relying on units with well-defined operational semantics and tool support. Specifically, Timed Automata with Tasks (TAT) in TIMES is chosen as the semantic unit with the purpose of anchoring different behavioral concerns of RTSSim models in all aspects. In this respect, model transformations are conducted at the meta-model level allowing the original operational semantics of RTSSim models to be preserved, while at the same time it can be presented in TIMES models in terms of a network of TAT.

  • 16.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Bate, Iain
    University of York.
    A statistical approach to simulation model validation in response-time analysis of complex real-time embedded systems2011In: Proceedings of the ACM Symposium on Applied Computing 2011, 2011, p. 711-716Conference paper (Refereed)
    Abstract [en]

    As simulation-based analysis methods make few restrictions on the system design and scale to very large and complex systems, they are widely used in, e.g., timing analysis of complex real-time embedded systems (CRTES) in industrial circles. However, before such methods are used, the analysis simulation models have to be validated in order to assess if they represent the actual system or not, which also matters to the confidence in the simulation results. This paper presents a statistical approach to validation of temporal simulation models extracted from CRTES, by introducing existing mature statistical hypothesis tests to the context. Moreover, our evaluation using simulation models depicting a fictive but representative industrial robotic control system indicates that the proposed method can successfully identify temporal differences between different simulation models, hence it has the potential to be considered as an effective simulation model validation technique. © 2011 ACM.

  • 17.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    A Statistical Approach for Validation of Task Simulation Models with Intricate Temporal Execution Dependencies2010In: Proceedings of the Work-In-Progress (WIP) track of 16th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS2010), 2010Conference paper (Refereed)
  • 18.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    On Validation of Simulation Models in Timing Analysis of Complex Real-Time Embedded Systems2010In: The 15th IEEE International Conference on Emerging Technologies and Factory Automation (EFTA'10), Work-In-Progress (WIP) session., Bilbao, 2010Conference paper (Refereed)
    Abstract [en]

    In this paper, we present work toward validating simulation models extracted from complex real-time embedded systems, from the perspective of response time and execution time of adhering tasks, by using the non-parametric two-sample Kolmogorov-Smirnov test. Moreover, we introduce a method of reducing the number of samples used in the analysis, while keeping the accuracy of results. The evaluation using a fictive but representative system model inspired by a real robotic control system with a set of change scenarios, shows a promising result: the proposed algorithm has the potential of assessing whether the extracted simulation model is a sufficiently accurate approximation of the target system.

  • 19.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Bate, Iain
    University of York.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Assessment of trace-differences in timing analysis for Complex Real-Time Embedded Systems2011In: SIES 2011 - 6th IEEE International Symposium on Industrial Embedded Systems, Conference Proceedings, 2011, p. 284-293Conference paper (Refereed)
    Abstract [en]

    In this paper, we look at identifying temporal differences between different versions of Complex Real-Time Embedded Systems (CRTES) by using timing traces representing response times and executiontimes of tasks. In particular, we are interested in being able to reason about whether a particular change to CRTES will impact on their temporal performance, which is difficult to answer due to the complicatedtiming behavior such CRTES have. To be specific, we first propose a sampling mechanism to eliminate dependencies existing in tasks' response time and execution time data in the traces taken from CRTES, which makes any statistical inference in probability theory and statistics realistic. Next, we use a mature statistical method, i.e., the non-parametric two-sample Kolmogorov-Smirnov test, to assess the possible temporal differences between different versions of CRTES by using timing traces. Moreover, we introduce a method of reducing the number of samples used in the analysis, while keeping the accuracy ofanalysis results. This is not trivial, as collecting a large amount of samples in terms of executing real systems is often costly. Our evaluation using simulation models describing an industrial robotic controlsystem with complicated tasks' timing behavior, indicates that the proposed method can successfully identify temporal differences between different versions of CRTES, if there is any. Furthermore, our proposed method outperforms the other statistical methods, e.g., bootstrap and permutation tests, that are often widely used in contexts, in terms of bearing on the accuracy of results when other methods have failed.

  • 20.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    An Approximate Timing Analysis Framework for Complex Real-Time Embedded Systems2010In: Proceedings - 2010 13th IEEE International Conference on Computational Science and Engineering, CSE 2010, 2010, p. 102-111Conference paper (Refereed)
    Abstract [en]

    To maintain, analyze and reuse many of today's Complex Real-Time Embedded Systems (CRTES) is very difficult and expensive, which, nevertheless, offers high business value in response to great concern in industry. In such context, not only functional behavior but also non-functional properties of systems have to be assured, i.e., Worst-Case Response Time (WCRT) of tasks has to be known. However, due to high complexity of such systems and the nature of the problem, the exact WCRT of tasks is impossible to find in practice, but may only be bounded. In addition, the existing relatively well developed theories for modeling and analysis of real-time systems are having problems which limit their application in the context. In this paper, we address this challenge by presenting a framework for approximate timing analysis of CRTES, namely AESIR-CORES, which provides a tight interval of WCRT estimates of tasks by the usage of two novel contributions. Our evaluation using three models inspired by two fictive but representative industrial CRTES indicates that AESIR-CORES can either successfully obtain the actual WCRT values, or have the potential to bound the unknown actual WCRT values from a statistical perspective.

  • 21.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    SICS.
    A Statistical Approach to Response-Time Analysis of Complex Real-Time Embedded Systems2010In: Proceedings of the 16th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA 2010), 2010, p. 153-160Conference paper (Refereed)
    Abstract [en]

    This paper presents RapidRT, a novel statistical approach to Worst-Case Response-Time (WCRT) analysis targeting complex embedded real-time systems. The proposed algorithm combines Extreme Value Theory (EVT) and other statistical methods in order to produce a probabilistic WCRT estimate. This estimate is calculated using response time data from either Monte Carlo simulations of a detailed model of the system, or from response-time measurements of the real system. The method could be considered as a pragmatic approach intended for complex industrial systems with real-time requirements. The target systems contain tasks with many intricate dependencies in theirtemporal behavior, which violates the assumptions of traditional analytical methods for response time analysis and thereby makes them overly pessimistic. An evaluation ispresented using two simulation models, inspired by an industrial robotic control system, and five other methods as reference.

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  • 22.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    A Statistical Approach to Simulation Model Validation in Timing Analysis of Complex Real-Time Embedded Systems2010In: Proceedings - 16th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2010, Brussels, 2010, p. -160, article id 5591317Conference paper (Refereed)
    Abstract [en]

    Simulation-based analysis methods make few restrictions on the system design and scale to very large and complex systems, therefore they are widely used in timing analysis of complex industrial embedded systems. This paper presents a statistical approach to validation of temporal simulation models extracted from complex embedded systems, by introducing existing mature statistical methods to the context. The proposed approach firstly collects sampling distributions of response time and execution time data of tasks in both the modeled system and the model, based on simple random samples (SRS). The second step of the approach is to compare the sampling distributions, regarding interesting timing properties, by using the non-parametric two-sample Kolmogorov-Smirnov test. The evaluation using a fictive system model inspired by a real robotic control system with a set of change scenarios, shows a promising result. The proposed algorithm can identify temporal differences between the target system and its extracted model, i.e., the algorithm can assess whether the extracted model is a sufficiently accurate approximation of the target system.

  • 23.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Statistical-based Response-Time Analysis of Systems with Execution Dependencies between Tasks2009In: Proceedings of the Work-In-Progress (WIP) track of the 30th IEEE Real-Time Systems Symposium (RTSS'09), Washington, DC, USA, 2009, p. 73-76Conference paper (Refereed)
  • 24.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Statistical-based Response-Time Analysis of Systems with Execution Dependencies between Tasks2010In: Proceedings of the IEEE International Conference on Engineering of Complex Computer Systems, ICECCS, 2010, p. 169-179Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel statistical-based approach to Worst-Case Response-Time (WCRT) analysis of complex real-time system models. These system models have been tailored to capture intricate execution dependencies between tasks, inspired by real industrial control systems. The proposed WCRT estimation algorithm is based on Extreme Value Theory (EVT) and produces both WCRT estimates together with a probability of being exceeded. By using the tools developed, an evaluation is presented using three different simulation models, and four other methods as reference: Monte Carlo simulation, MABERA, HCRR and traditionalResponse-Time Analysis (basic RTA). Empirical results demonstrate that the benefit of the proposed approach, in terms of 1) reduced pessimism when compared to basic RTA and 2) validated guarantee of never being less than the actual response time values. The proposed approach also needs much fewer simulations compared to other three simulation-based methods.

  • 25.
    Nemati, Farhang
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    A Framework for Real-Time Systems Migration to Multi-Cores2009Report (Other academic)
    Abstract [en]

    Power consumption and thermal problems limit a further increase of speed in single-core processors. Processor architects are therefore moving toward multicore processors. However, a shift to multi-core processors is a big challenge for developers of embedded real-time systems, especially considering existing “legacy” systems which have been developed with single-core processor assumptions. These systems have been developed and maintained by many developers over many years, and cannot easily be replaced due to the huge development investments they represent. In this paper we investigate challenges of migrating complex legacy real-time systems to multi-core architectures. We propose a partitioning algorithm to prepare the migration. Partitioning groups task and maps them to the different cores on the multicore processor, increasing system performance while ensuring correctness. We have run experiments that compare outputs of the algorithm to the outputs of an exhaustive search. Based on a cost function, the algorithm produces systems very close to optimal partitioning with respect to the cost function.

  • 26.
    Nemati, Farhang
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Towards Migrating Legacy Real-Time Systems to Multi-Core Platforms2008In: IEEE International Conference on Emerging Technologies and Factory Automation, ETFA, 2008, p. 717-720Conference paper (Refereed)
    Abstract [en]

    Power consumption and thermal problems limit the single-core processors to be faster. Processor architects are therefore moving toward multi-coreprocessors. Developers of embedded real-time systems however hesitates a shift to multi-core processors, especially for existing "legacy" systemswhich have been developed with single-core processor assumptions. These systems have been developed and maintained by many developers over many years, and can not easily be replaced due to the huge development investments they represent. In this paper we investigate challenges ofmigrating complex legacy real-time systems to multi-core architectures. We propose componentization and partitioning to prepare the migration. Componentization groups logically related tasks into components (or subsystems). This provides an abstraction layer from a scheduling perspective, which facilitates migration. Partitioning maps tasks to the different cores on the multi-core processor, maximizing system performance while ensuring correctness.

  • 27.
    Nemati, Farhang
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Validation of Temporal Simulation Models of Complex Real-Time Systems2008In: IEEE International Workshop On Component-Based Design Of Resource-Constrained Systems (CORCS'08), Turku, Finland, 2008, p. 1335-1340Conference paper (Refereed)
    Abstract [en]

    Model based analysis has the potential to facilitate maintenance of complex real-time systems, as it allows for impact analysis with respect to thesystems' temporal behavior. Model based analysis of temporal behavior of a legacy real-time system has also the potential to support migration toward component based system. However, since most software systems today have been developed in a traditional, code oriented manner, sufficiently detailed models are typically not available. To apply model based analysis on these systems, models have to be extracted from their implementation and observed run-time behavior. This requires methods for model validation. The paper proposes a novel method for model validation and presents a framework for evaluation of model validation methods, which will be used to evaluate the proposed method. The method is targeting temporalmodels extracted from complex real-time systems. 

  • 28.
    Åsberg, Mikael
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Kraft, Johan
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Kato, Shinpei
    Mälardalen University, School of Innovation, Design and Engineering.
    A loadable task execution recorder for Linux2010In: Proceedings of the 1st International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems, Brussels, Belgium, 2010Conference paper (Refereed)
1 - 28 of 28
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