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  • 151.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Kato, Shinpei
    Nagoya University, Nagoya, Japan.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    An Adaptive Server-Based Scheduling Framework with Capacity Reclaiming and Borrowing2014In: RTCSA 2014 - 20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, 2014, p. Article number 6910548-Conference paper (Refereed)
    Abstract [en]

    In this paper, we present a new reservation based scheduling framework for soft real-time systems using EDF algorithm (called CARB-EDF). This framework has the features of Capacity Adaptation, Reclaiming and Borrowing. This framework can simplify the initial configuration of the system, where the system designer does not need to provide any estimations of task execution times. We also present a Chebyshev’s inequality based predictor to estimate task execution times. A number of simulation-based experiments have been implemented. According to the results compared with some related works, our scheduling framework can provide a better performance with acceptable extra scheduling overhead. 

  • 152.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    A Stochastic Response Time Analysis for Communications in On-Chip Networks2015Conference paper (Refereed)
    Abstract [en]

    Priority-based wormhole-switching has been proposed as a solution to handle real-time traffic in on-chip networks. In order to support real-time traffic, the predictability of end-toend delays need to be guaranteed. Several deterministic schedulability analysis approaches for wormhole-switched networks have been proposed. These approaches calculate a single upper-bound of the response time of each Network-on-Chip (NoC) flow, which is suitable for hard real-time applications. However, for many soft real-time applications, the performance does not depend on the worst-case scenario, which means that the calculated single upper-bounds are not sufficient to represent the performance. Therefore, in this paper, we present a stochastic Response Time Analysis (RTA) which can calculate a distribution of the response times of a real-time NoC flow. The estimated distributions can be utilized for multiple purposes, such as calculating deadline miss ratios, and computing upper-bounds regarding different probabilities. A number of simulation-based experiments are generated in order to investigate the pessimism involved in the analysis. Moreover, the processing time of the analysis is also measured from the experiments in order to examine the scalability of the proposed approach.

  • 153.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    An EVT-based Worst-Case Response Time Analysis of Complex Real-Time Systems2013In: Proceedings of the 8th IEEE International Symposium on Industrial Embedded Systems, SIES 2013, 2013, p. 249-258Conference paper (Refereed)
    Abstract [en]

    In recent years, the complexity of real-time embedded systems has increased dramatically. For those modern real-time systems, the limitations of original static Response Time Analysis (RTA) become more and more conspicuous. Most static analysis methods not only require much detailed system information, but also only target to some specific system model with non-realistic assumptions. As a result, those methods may produce overly pessimistic results, making them unsuitable to be applied on a complex industrial system. The best system model may be the system itself. Therefore, statistical RTA, which can produce probabilistic analysis results based on samples provided by real systems or simulators, may become more expedient. Statistical RTA usually requires more relaxed assumptions and less system information than static RTA. In this paper, we present an Extreme Value Theory (EVT) based method to compute Worst-Case Response Time (WCRT) targeting complex real-time systems. In the evaluation phase, we have applied this method to the calculation of worst-case transmission delays of messages over Controller Area Network (CAN), and some comparisons with static RTA are also provided. According to the experimental results, as the system complexity increases, our approach performs much more stable and less pessimistic.

  • 154.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Applying the Peak Over Thresholds Method on Worst-Case Response Time Analysis of Complex Real-Time Systems2013In: 2013 IEEE 19th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2013, 2013, p. 22-31Conference paper (Refereed)
    Abstract [en]

    The predictability of timing behavior is a very important performance issue of a real-time system. As the complexity of modern industrial systems increases, analyzing the timing behaviors of those systems becomes more and more challenging. Most of the existing analysis methods depend on static and detailed information of the systems under analysis. However, sometimes only partial information of a system can be available, or it may require too much effort on obtaining those details, making those analysis methods much less feasible. Moreover, those methods usually focus on some specific system models with unrealistic assumptions, consequently, applying those methods on a complex industrial real-time system may result in overly pessimistic results. Therefore, in this paper, we propose a statistical method to compute Worst-Case Response Times (WCRTs) of complex real-time systems regarding soft timing constraints, which can provide a higher general applicability with less required system information. Our approach employs a Peak Over Thresholds (POT) method, which is a branch of the Extreme Value Theory (EVT). For the evaluation, we have applied this approach on the analysis of message transmission latencies over Controller Area Networks (CAN).

  • 155.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Schedulability analysis of GMF-modeled messages over controller area networks with mixed-queues2014In: IEEE Int. Workshop Factory Commun. Syst. Proc. WFCS, 2014, p. Article number 6837606-Conference paper (Refereed)
    Abstract [en]

    The Controller Area Network (CAN) is widely utilized in many industrial real-time applications. As a real-time communication network, the predictability of timing behaviors is very important. Therefore, many works have been proposed regarding the schedulability analysis of CAN messages. Most of the existing analysis approaches are based on a traditional periodic message model. However, in some applications, the transmission of a message may follow a certain pattern instead of repeating the same transmission period by period. In these cases, applying the existing analysis methods may lead to quite pessimistic results. In order to tackle this problem, in this paper we apply the Generalized Multi-Frame (GMF) task model on CAN messages, where both priority-based and FIFO-based message queues are taken into account. We present a corresponding sufficient schedulability analysis. According to the experimental evaluations, our analysis can provide tighter results compared to the existing CAN message response time analysis in the context of GMF-modeled messages. 

  • 156.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Schedulability analysis of Multi-Frame messages over Controller Area Networks with mixed-queues2013Conference paper (Refereed)
    Abstract [en]

    The Controller Area Network (CAN) is one of the most widely utilized real-time communication networks, which has plenty of applications especially in automotive industry. Many works have been proposed regarding the CAN schedulability analysis which is very important for guaranteeing the safety and reliability of hard real-time systems. Most of the existing analysis methods assume a periodic message model, and some of them take sporadic messages into account. However, for some applications, message transmissions may follow a specific pattern instead of repeating the same transmission period by period, where applying the existing methods may include much pessimism. In this paper, we apply the Multi-Frame task model, which is first proposed by Mok and Chen in cite{MokChen}, on CAN messages. Moreover, we assume that the ECUs in the analyzed network can employ both FIFO and priority based queues. The schedulability analysis and the corresponding proofs are provided along with a case study.

  • 157.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Almeida, Luis
    University of Porto.
    Response time analysis for static priority based SpaceWire networks2012In: Proceeings of the 2nd International Workshop on Worst-Case Traversal Time (WCTT '12), 2012, p. 7-14Conference paper (Refereed)
    Abstract [en]

    The SpaceWire network standard is used in spacecraft communications and has been selected for future ESA satellites. In order to guarantee the safety and reliability of on-board systems, the designers have to make sure that all critical timing constraints are satisfied. The SpaceWire network is a wormhole based network which makes its timing analysis significantly complex. Some methods for computing upper-bounds of end-to-end delays of certain wormhole network models have been developed. However, those models require some explicit assumptions and dedicated real-time mechanisms which cannot be supported by the current SpaceWire networks. Moreover, some work has proposed analysis approaches for SpaceWire networks assuming the Round-Robin arbitration scheme only. In this paper, we focus on the priority based arbitration scheme instead and we propose a worst-case response time analysis to evaluate the end-to-end delays of traffic transmissions in SpaceWire networks. The corresponding proofs to our analysis are presented along with a case study. © 2012 ACM.

  • 158.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Chiru, Cezar
    Mälardalen University.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Sandström, Kristian
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    On providing real-time guarantees in cloud-based platforms2016In: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, 2016, article id Article number 7496534Conference paper (Refereed)
    Abstract [en]

    Cloud technologies are gaining more and more attentions in recent years. Cloud-based service brings benefits in cost, energy efficiency, sharing of resources, increased flexibility, adaptability and evolvability. However, there are a number of associated challenges that need to be properly addressed before applying the cloud technique generally in industries. Providing efficient and predictable computation and communication is one of the important challenges, since many industrial systems (e.g. a control system) have specific timing requirements. Our current work thus focuses on guaranteeing the predictability of a cloud-based service. Virtualization, as one of the key technologies in Cloud Computing, is used to abstract details of resources away from end-services which simplifies the resource sharing. It thus improves the resource utilization and saves budget for end-users. In this preliminary work, we have implemented a distributed system using virtualization techniques (including virtual machines and virtual switches). Additionally, we generate a number of experiments to investigate how QoS policies can help us to provide real-time communication guarantees. 

  • 159.
    Liu, Meng
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Mubeen, Saad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards Stochastic Response Time Analysis for CAN Messages with Multiple Probabilistic Factors2015In: The 21st IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, WiP RTCSA-wip'15, Hong Kong, HongKong, 2015Conference paper (Refereed)
    Abstract [en]

    Controller Area Network (CAN) is a widely used real-time network in the vehicular domain. In this paper we identify and discuss two practical parameters, namely message copy time and mixed transmission pattern, that can vary randomly during the execution of the system. We propose to leverage on these parameters to extend the existing stochastic Response Time Analysis (RTA) for CAN.

  • 160.
    Lo Bello, Lucia
    et al.
    University of Catani.
    Kaczynski, Giordano A.
    University of Catania.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Towards a robust real-time wireless link in a land monitoring application2006In: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA, 2006, p. 449-452Conference paper (Refereed)
    Abstract [en]

    This paper addresses on-going work on providing a model of a robust real-time wireless link intended to be used to connect a mobile platform to a ground station in a land monitoring system. This work is part of a project where the mobile platform is an Unmanned Aerial Vehicle (UAV), equipped with embedded devices which acquire and process sensor data to be sent to the ground station. Firstly, a temporal model of the communications link relying on radio modems is developed. Secondly, measurements have been made in order to determine packet loss probability. These two results are currently used to provide a robust real-time model of the wireless communications link.

  • 161. Lo Bello, Lucia
    et al.
    Kaczynski, Giordano A.
    Nolte, Thomas
    Mälardalen University, Department of Computer Science and Electronics.
    Sorbello, Gino
    Sgro, Francesco
    Mirabella, Orazio
    An approach to support UAV to ground station real-time communications in a land monitoring system2006Conference paper (Refereed)
  • 162.
    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)
  • 163.
    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.

  • 164.
    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.

  • 165.
    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)
  • 166.
    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.

  • 167.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    An Evaluation Framework for Complex Industrial Real-Time Embedded Systems2012Report (Other academic)
    Abstract [en]

    In this technical report, we introduce an evaluation framework which are centering around four base models, inspired by an industrial robotic control application. Specifically, such evaluation models are quite complicated from a task execution and temporal dependencies perspective, making difficult to perform the corresponding timing analysis.

  • 168.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    On Using Extreme Value Theory in Response-Time Analysis of Priority-Driven Periodic Real-Time Systems2010In: The 31st IEEE Real-Time Systems Symposium (RTSS'10), Work-In-Progress (WIP) session, San Diego, CA, USA, 2010Conference paper (Refereed)
  • 169.
    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.
    Cucu-Grosjean, Liliana
    INRIA Nancy-Grand Est, Nancy, France.
    A New Way about using Statistical Analysis of Worst-Case Execution Times2011In: ACM SIGBED Review, ISSN 1551-3688, Vol. 8, no 3, p. 11-14Article in journal (Refereed)
    Abstract [en]

    In this paper, we revisit the problem of using Extreme Value Theory (EVT) in the Worst-Case Execution Time (WCET) analysis of the programs running on a single processor. Our proposed statistical WCET analysis method consists of a novel sampling mechanism tackling with some problems that hindered the application of using EVT in the context, and a statistical inference about computation of a WCET estimate of the target program. To be specific, the presented sampling mechanism takes analysis samples from the target program based around end-to-end measurements. Next, the statistical inference using EVT together with other statistical techniques, analyzes such timing traces which contain the execution time data of the program, to compute a WCET estimate with a certain predictable probability of being exceeded.

  • 170.
    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.
    Cucu-Grosjean, Liliana
    INRIA Nancy-Grand Est.
    A statistical response-time analysis of complex real-time embedded systems by using timing traces2011In: SIES 2011 - 6th IEEE International Symposium on Industrial Embedded Systems, Conference Proceedings, 2011, p. 43-46Conference paper (Refereed)
    Abstract [en]

    Real-time embedded systems are becoming ever more complex, and we are reaching the stage where even if static Response-Time Analysis (RTA) was feasible from a cost and technical perspective, the results are overly pessimistic making them less useful to the practitioner. When combined with the fact that most timing analysis tends to be statistical in nature, this suggests there should be a move towardstatistical RTA. However, to make such analysis useful, it is imperative that we have evidence that the statistical RTA and the information analyzed is sufficiently accurate. In this paper we present and validatea technique for statistical RTA that can cope with systems that are complex from both a size and tasks' dependencies perspective. This claim is backed up by our evaluation using information from realindustrial control systems.

  • 171.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Bate, Iain
    Mälardalen University, School of Innovation, Design and Engineering.
    Cucu-Grosjean, Liliana
    INRIA Nancy-Grand Est.
    A statistical response-time analysis of real-time embedded systems2012In: Proceedings - Real-Time Systems Symposium, 2012, 2012, p. 351-362Conference paper (Refereed)
    Abstract [en]

    Real-time embedded systems are becoming ever more complex. We are reaching the stage where even if static Response-Time Analysis (RTA) was feasible from a cost and technical perspective, the results of such an analysis are overly pessimistic. This makes them less useful to the practitioner. In addition, the temporal validation and verification of such systems in some applications, e.g., aeronautics, requires the probability of obtaining a worst-case response time larger than a given value in order to support dependable system functions. All these facts advocate moving toward statistical RTA, which instead of calculating absolute worst-case timing guarantees, computes a probabilistic worst-case response time estimate. The contribution of this paper is to present and evaluate such a statistical RTA technique which uses a black box view of the systems under analysis, by not requiring estimates of parameters such as worst-case execution times of tasks. Furthermore, our analysis is applicable to real systems that are complex, e.g., from a task dependencies perspective.

  • 172.
    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.
    Cucu-Grosjean, Liliana
    INRIA Nancy-Grand Est, Nancy, France.
    A Trace-Based Statistical Worst-Case Execution Time Analysis of Component-Based Real-Time Embedded Systems2011In: 2011 IEEE 16TH CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA) / [ed] Mammeri, Z., New York: IEEE , 2011Conference paper (Refereed)
    Abstract [en]

    This paper describes the tool support for a framework for performing statistical WCET analysis of real-time embedded systems by using bootstrapping sampling and Extreme Value Theory (EVT). To be specific, bootstrapping sampling is used to generate timing traces, which not only fulfill the requirements given by statistics and probability theory, but also are robust to use in the context of estimating the WCET of programs. Next, our proposed statistical inference uses EVT to analyze such timing traces, and computes a WCET estimate of the target program, pertaining to a given predictable probability. The evaluation results show that our proposed method could have the potential of being able to provide a tighter upper bound on the WCET estimate of the programs under analysis, when compared to the estimates given by the referenced WCET analysis methods.

  • 173.
    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.

  • 174.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Bate, Iain
    Mälardalen University, School of Innovation, Design and Engineering.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Timing Analyzing for Systems with Execution Dependencies between Tasks2010In: Proceedings of the ACM Symposium on Applied Computing 201, 2010, p. 357-358Conference paper (Refereed)
    Abstract [en]

    In this paper, a novel approach to timing analysis of complex real-time systems with intricate execution dependencies between tasks, such as asynchronous message-passing and globally shared state variables, is presented. By applying the method to a model taken from a real robotic control system, we show the benefit, in terms of reduced pessimism, when compared to a combination of standard static WCET analysis and Response-Time Analysis.

  • 175.
    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.
    Norström, Christer
    Mälardalen University, School of Innovation, Design and Engineering.
    Timing analyzing for systems with task execution dependencies2010In: Proceedings - International Computer Software and Applications Conference, 2010, p. 515-524Conference paper (Refereed)
    Abstract [en]

    This paper presents a novel approach to timing analysis of complex real-time systems containing data-driven tasks with intricate executiondependencies. Using a system model inspired by industrial control systems, we show how the execution time of tasks can be represented as a mathematical expression instead of a single numeric value. Next, based on this more detailed modeling, we introduce a concrete process of formally obtaining the exact value of both Worst-Case Execution-Time (WCET) and Worst-Case Response-Time (WCRT) of tasks by using upper-part binary search and TIMES (a timed model checker). Finally, in order to show the potential of the proposed approach, we apply it to a model created from a real robotic control system for which the traditional way of obtaining a WCET estimate (through static WCET analysis) on tasks for usage in basic RTA is not appropriate. Our results indicate a significant reduction of pessimism when compared to basic RTA using WCET estimates on tasks given by a basic assumption.

  • 176.
    Lu, Yue
    et al.
    Mälardalen University, School of Innovation, Design and Engineering. INRIA Nancy-Grand Est, Nancy, France.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Cucu-Grosjean, Liliana
    INRIA Nancy-Grand Est, Nancy, France.
    Bate, Iain
    University of York, York, United Kingdom.
    RapidRT: A Tool For Statistical Response-Time Analysis of Complex Industrial Real-Time Embedded Systems2011Conference paper (Refereed)
    Abstract [en]

    RapidRT is a tool for statistical response time analysis of Complex Industrial Real-Time Embedded Systems (CIRTES). A key feature of this tool is that it does not require worst-case execution times of tasks to be known for the computation of a probabilistic task worst-case response time estimate. The presented tool is a step towards bridging the gap between academic research and industrial practice.

  • 177.
    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.

  • 178.
    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.

  • 179.
    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.

  • 180.
    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)
  • 181.
    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.

  • 182. Marau, Ricardo
    et al.
    Almeida, Luis
    Mälardalen University, School of Innovation, Design and Engineering.
    Pedreiras, Paulo
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Towards Server-based Switched Ethernet for Real-Time Communications2008Conference paper (Refereed)
  • 183.
    Marau, Ricardo
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Figueiredo, Nuno
    Mälardalen University, School of Innovation, Design and Engineering.
    Santos, Rui
    Mälardalen University, School of Innovation, Design and Engineering.
    Pedreiras, Paulo
    Mälardalen University, School of Innovation, Design and Engineering.
    Almeida, Luis
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Server-based real-time communications of Switched Ethernet2008In: Proceedings of the 1st Workshop on Compositional Theory and Technology for Real-Time Embedded Systems (CRTS'08) in conjunction with the 29th IEEE International Real-Time Systems Symposium (RTSS'08), Barcelona, Spain, 2008Conference paper (Refereed)
  • 184.
    Martin, G.
    et al.
    Tensilica Inc, Santa Clara, CA, United States.
    Lavagno, L.
    Cadence Berkeley Laboratory, Berkeley, CA, United States.
    Hansson, Hans
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolin, Mikael
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Thramboulidis, K.
    University of Patras, Patras, Greece.
    Embedded systems  - An Overview2017In: Systems, Controls, Embedded Systems, Energy, and Machines, Boca Raton: CRC Press , 2017, p. 16-1-16-1Chapter in book (Other academic)
    Abstract [en]

    Embedded systems span a number of scienti?c and engineering disciplines, which evolve continuously. So does the ?eld of embedded systems. To write on this topic requires a careful choice of the material to be covered, to make a presentation of a reasonable length, and provide a fairly up-to-date material. This chapter focuses on two main areas of embedded systems, which have evolved only in recent years, namely, systems on a chip and networked embedded systems. The section on System-on-Chip surveys a large number of the issues involved in its design. The section on networked embedded systems presents an overview of trends for networking of embedded systems, their design, and their application for in-car controls and automation. This material is preceded by a round up of embedded systems in general, and design trends. 

  • 185.
    Mifdaoui, Ahlem
    et al.
    University of Toulouse, France.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Pedreiras, Paulo
    University of Aveiro, Portugal.
    Almeida, Luis
    University of Porto, Portugal.
    Marau, Ricardo
    University of Porto, Portugal.
    Exploring alternatives to use master/slave full duplex switched Ethernet for avionics embedded applications2012Conference paper (Refereed)
    Abstract [en]

    The complexity of distributed real-time systems, including military embedded applications, is increasing due to an increasing number of nodes, their functionality and higher amounts of exchanged data. This higher complexity imposes major development challenges when nonfunctional properties must be enforced. On the other hand, the current military communication networks are a generation old and are no longer effective in facing such increasingly complex requirements. A new communication network, based on Full Duplex Switched Ethernet and Master/slave approach, has been proposed previously. However, this initial approach is not efficient in terms of network bandwidth utilization. In this paper we propose two new alternative approaches that can use the network bandwidth more efficiently. In addition we provide a preliminary qualitative assessment of the three approaches concerning different factors such as performance, scalability, complexity and flexibility.

  • 186.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Adaptive Hierarchical Scheduling Framework: Configuration and Evaluation2013Report (Other academic)
    Abstract [en]

    We have introduced an adaptive hierarchicalscheduling framework as a solution for composing dynamic realtime systems, i.e., systems where the CPU demand of its tasks aresubjected to unknown and potentially drastic changes during runtime. The framework consists of a controller which periodicallyadapts the system to the current load situation. In this paper,we unveil and explore the detailed behavior and performanceof such an adaptive framework. Specifically, we investigate thecontroller configurations enabling efficient control parameterswhich maximizes performance, and we evaluate the adaptiveframework against a traditional static one.

  • 187.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Adaptive Hierarchical Scheduling Framework: Configuration and Evaluation2013Conference paper (Refereed)
    Abstract [en]

    We have introduced an adaptive hierarchical scheduling framework as a solution for composing dynamic real-time systems, i.e., systems where the CPU demand of its tasks are subjected to unknown and potentially drastic changes during run-time. The framework consists of a controller which periodically adapts the system to the current load situation. In this paper, we unveil and explore the detailed behavior and performance of such an adaptive framework. Specifically, we investigate the controller configurations enabling efficient control parameters which maximizes performance, and we evaluate the adaptive framework against a traditional static one. Furthermore, we demonstrate the results of our investigation using a practical multimedia case study in which we simulate the timing behavior of video decoding tasks running on our proposed framework. In addition, we compare the results of using our framework with the results of using static resource allocation approach.

  • 188.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Exact and Approximate Supply Bound Function for Multiprocessor Periodic Resource Model: Unsynchronized Servers2012Conference paper (Refereed)
    Abstract [en]

    The Multi Processor Periodic Resource (MPR) model has been proposed for modeling compositional real-time systems which run on a shared multi processor hardware. In this paper we extend the MPR model such that the execution of virtual processors (servers) is not assumed to be synchronized i.e., the servers can have different phases. We believe that relaxing the server synchronization requirement provides greater deal of compatibility for implementing such a compositional method on various hardware platforms. We derive the resource supply bound function of the extended MPR model using an algorithm. Furthermore, we suggest an approach to calculate an approximate supply bound function with lower computational complexity for systems where calculating their supply bound function is computationally expensive.

  • 189.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Implementation of the Multi-Level Adaptive Hierarchical Scheduling Framework2013In: Proceedings of OSPERT 2013, 2013, p. 11-19Conference paper (Refereed)
    Abstract [en]

    We have presented a multi-level adaptive hierarchical scheduling framework in our previous work. The framework targets compositional real-time systems which are composed of both hard and soft real-time systems. While static CPU portions are reserved for hard real-time components, the CPU portions of soft real-time components are adjusted during run-time. In this paper, we present the implementation details of our framework which is implemented as a Linux kernel loadable module. In addition, we present a case-study to evaluate the performance and the overhead of our framework.

  • 190.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Multi-Level Adaptive Hierarchical Scheduling Framework for Composing Real-Time Systems2013In: 2013 IEEE 19th International Conference on Embedded and Real-Time Computing Systems and Applications, RTCSA 2013, 2013, p. 320-329Conference paper (Refereed)
    Abstract [en]

    Processor partitioning and hierarchical scheduling have been widely used for composing hard real-time systems on a shared hardware platform while preserving the timing requirements of the systems. Due to the safety critical nature of the hard real-time systems for deriving the sufficient partition size often conservative analysis is used. Applying the exact same analysis for deriving the partition sizes for soft real-time systems result in unnecessary processors overallocation and consequently waste of the CPU resource. In this paper, to address the problem of composing soft and hard real-time systems on a resource constrained shared hardware, we present a multi-level adaptive hierarchical scheduling framework. In our framework, we adapt the processor partition sizes of soft real-time systems according to their need at each time point by on-line monitoring their processor demand. Furthermore, we implement our adaptive framework in the Linux kernel and show the performance of our framework using a case-study.

  • 191.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Åsberg, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    On Adaptive Hierarchical Scheduling of Real-time Systems Using a Feedback Controller2011In: 3rd Workshop on Adaptive and Reconfigurable Embedded Systems (APRES'11), 2011Conference paper (Refereed)
    Abstract [en]

    Hierarchical scheduling provides predictable timing and temporal isolation; two properties desirable in real-time embedded systems. In hierarchically scheduled systems, subsystems should receive a sufficient amount of CPU resources in order to be able to guarantee timing constraints of its internal parts (tasks). In static systems, an exact amount of CPU resource can be allocated to a subsystem. However, in dynamic systems, where execution times of tasks vary considerably during runtime, it is desirable to give a dynamic portion of the CPU given the current load situation. In this paper we present a feedback control approach for adapting the amount of CPU resource that is allocated to subsystems during run-time such that each subsystem receives sufficient resources while keeping the number of deadline violations to a minimum. We also show an example simulation where the controller adapts the budget of a subsystem.

  • 192.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Spampinato, Giacomo
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Bandwidth Adaptation in Hierarchical Scheduling Using Fuzzy Controllers2012In: 7th IEEE International Symposium on Industrial Embedded Systems, SIES 2012 - Conference Proceedings, 2012, p. 148-157Conference paper (Refereed)
    Abstract [en]

    In our previous work, we have introduced an adaptive hierarchical scheduling framework as a solution for composing dynamic real-time systems, i.e., systems where the CPU demand of their tasks are subjected to unknown and potentially drastic changes during run-time. The framework uses the PI controller which periodically adapts the system to the current load situation. The conventional PI controller despite simplicity and low CPU overhead, provides acceptable performance. However, increasing the pressure on the controller e.g, with an application consisting of multiple tasks with drastically oscillating execution times, degrades the performance of the PI controller. Therefore, in this paper we modify the structure of our adaptive framework by replacing the PI controller with a fuzzy controller to achieve better performance. Furthermore, we conduct a simulation based case study in which we compose dynamic tasks such as video decoder tasks with a set of static tasks into a single system, and we show that the new fuzzy controller outperforms our previous PI controller.

  • 193.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Lelli, Juri
    Scuola Superiore Sant’Anna, Italy.
    Lipari, Giuseppe
    Scuola Superiore Sant’Anna, Italy and LSV - ENS Cachan, France.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Towards Energy-aware Multiprocessor Hierarchical Scheduling of Real-time Systems2013Conference paper (Refereed)
    Abstract [en]

    Multiprocessor platforms are becoming increasingly more popular. Providing more computation capacity on a single hardware platform, multiprocessors make it possible to integrate previously federated real-time systems onto a single platform. Multiprocessor hierarchical scheduling techniques provide the ground for composing real-time components, while guaranteeing the timing correctness of the composed system. A considerable deal of compositional real-time systems are embedded systems that operate on battery power. In such systems, reducing the power consumption is of paramount importance to increase the system lifetime. In this paper, we present our idea on reducing the energy consumption when performing hierarchical scheduling on multiprocessors. We formulate the problem, present the model and sketch the outline of the solution. Finally, we present a number of challenges which will be addressed in our work.

  • 194.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Liu, Meng
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering. Embedded Systems.
    Probabilistic Application Interfaces for Hierarchical Scheduling2013In: IEEE Real-Time Systems Symposium: IEEE Real-Time Systems Symposium Work-in-Progress (WiP) session, Vancouver, Canad, 2013Conference paper (Refereed)
  • 195.
    Moghaddami Khalilzad, Nima
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering.
    Åsberg, Mikael
    Mälardalen University, School of Innovation, Design and Engineering.
    Towards Adaptive Hierarchical Scheduling of Real-Time Systems2011In: IEEE Symposium on Emerging Technologies and Factory Automation, ETFA, 2011 / [ed] Mammeri, Z., New York: IEEE , 2011, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Hierarchical scheduling provides a modular framework for integrating, scheduling and guaranteeing timing constraints of compositional real-time systems. In such a scheduling framework, all modules should receive a sufficient portion of the shared CPU to be able to guarantee timing constraints of their internal parts. In dynamic systems i.e., systems where the execution time of tasks are subjected to sudden and drastic changes during run-time, assigning fixed CPU portions to the modules is conducive to either low CPU utilization or numerous task deadline misses. In this paper, in order to address this problem, we propose an adaptive CPU allocation method which dynamically assigns CPU portions to the modules during run-time based on their current CPU demand. Besides, the presented approach is evaluated using a series of different simulations. In addition, we present a method for scheduling modules in situations when the CPU resource is not sufficient for scheduling all modules. We introduce the notion of module (subsystem) criticality, and in an overload situation we distribute the CPU resource based on the criticality of modules.

  • 196.
    Mubeen, Saad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ashjaei, Mohammad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Integrating Response-Time Analyses for Heterogeneous Automotive Networks in MPS-CAN Analyzer2015In: 6th International Workshop on Analysis Tools and Methodologies for Embedded and Real-time Systems WATERS 2015, 2015Conference paper (Refereed)
    Abstract [en]

    MPS-CAN analyzer is a research tool that supports the Response Time Analysis (RTA) for Controller Area Network (CAN). It takes into account various queueing policies; buffer limitations in the CAN controllers; and mixed transmission patterns supported by the higher-level protocols. In this paper, we extend the MPS-CAN analyzer to support RTA of heterogeneous automotive networks. Within this context, first we implement RTA for Ethernet Audio/Video Bridging (AVB) messages in a single-switch architecture. We then integrate the analyses for CAN and Ethernet AVB by exploiting the analysis for CAN to Ethernet AVB gateway. With this integration, the MPS-CAN analyzer supports the analysis for heterogeneous messages that traverse through heterogeneous networks consisting of CAN and Ethernet AVB. We also evaluate the newly implemented analyses by conducting an automotive-application case study.

  • 197.
    Mubeen, Saad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ashjaei, Mohammad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundbäck, J.
    Arcticus Systems AB, Järfälla, Sweden .
    Lundbäck, K-L
    Arcticus Systems AB, Järfälla, Sweden .
    Integrating Response-time Analysis for Heterogeneous Networks with Rubus Analysis Framework: Challenges and Preliminary Solutions2015In: 2015 IEEE 20th Conference on Emerging Technologies & Factory Automation (ETFA 2015): Proceedings of a meeting held 8-11 September 2015, Luxembourg., 2015Conference paper (Refereed)
    Abstract [en]

    In this paper we discuss the challenges that are faced when the state-of-the-art research results are transferred to a model-based tool chain for the industrial use. These challenges are often overlooked when the research results are implemented in an academic environment. In particular, we discuss various challenges regarding the implementation and integration of the response-time analysis for heterogeneous networks, comprising of CAN and Ethernet AVB, as a plug-in for the Rubus Analysis Framework. Rubus tool suite is used for the model- and component-based development of software for vehicular real-time systems by several international companies. We also discuss preliminary solutions to deal with the challenges.

  • 198.
    Mubeen, Saad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Ashjaei, Mohammad
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Lundbäck, John
    Arcticus Systems AB, Järfälla, Sweden.
    Gålnander, Mattias
    Arcticus Systems AB, Järfälla, Sweden.
    Lundbäck, Kurt-Lennart
    Arcticus Systems AB, Järfälla, Sweden.
    Modeling of End-to-end Resource Reservations in Component-based Vehicular Embedded Systems2016In: Software Engineering and Advanced Applications (SEAA), 2016 42th Euromicro Conference on, 2016, p. 283-292Conference paper (Refereed)
    Abstract [en]

    There is a plethora of models, techniques and toolsthat support model- and component-based software developmentof vehicular distributed embedded systems. However, a large ma-jority of them have a limited or no support to model and specifyend-to-end resource reservations on the software architecturesof these systems. Resource reservations allow flexibility duringthe development and execution of such complex systems withoutjeopardizing their predictable behavior. As a result, severalapplications in the system that share the same hardware platformcan be developed independently. In this paper we identify severalrequirements that any existing component model should fulfill inorder to support the modeling of end-to-end resource reservationson the software architectures of such systems. As a proof ofconcept, we extend the Rubus Component Model (RCM) byfulfilling these requirements. RCM is used for the development ofcontrol functionality in vehicular embedded systems by severalinternational companies. We also provide a technique to extractexecution models from the software architectures of these systemswith resource reservations. In order to show the usability of ourtechnique, we model a vehicular distributed embedded systemwith the extended component model and extract the executionmodel from the software architecture augmented with end-to-endresource reservations.

  • 199.
    Mubeen, Saad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Becker, Matthias
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Zhao, Xiaosha
    Mälardalen University.
    Gan, Lingjian
    Mälardalen University.
    Behnam, Moris
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Towards automated deployment of IEC 61131-3 applications on multi-core systems2016In: IEEE International Workshop on Factory Communication Systems - Proceedings, WFCS, 2016, article id Article number 7496531Conference paper (Refereed)
    Abstract [en]

    The IEC 61131-3 standard, a widely used standard in the automation industry, defines various programming languages for programmable logic controllers. Today, the open source tools that comply with this standard do not support deployment of the applications on multi-core platforms. In this paper, we introduce a novel multi-step approach that aims to support automatic deployment of the automation control applications, developed using the IEC 61131-3 standard, to multi-core platforms. In the first step, the generated sequential code is partitioned. In the second step, the partitioned code is allocated to tasks while the tasks are mapped to various cores, without violating the dependencies, synchronization and communication constraints in the application. In order to provide a proof of concept, we develop a prototype by extending an existing tool that complies with the standard. We also perform a case study and a preliminary evaluation of the prototype. 

  • 200.
    Mubeen, Saad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Nolte, Thomas
    Mälardalen University, School of Innovation, Design and Engineering, Embedded Systems.
    Applying End-to-end Path Delay Analysis to Multi-rate Automotive Systems Developed using Legacy Tools2015In: 11th IEEE World Conference on Factory Communication Systems WFCS'15, Institute of Electrical and Electronics Engineers Inc. , 2015, Vol. July, p. Article number 7160585-Conference paper (Refereed)
    Abstract [en]

    The end-to-end path delay analysis is used to predict timing behavior of multi-rate automotive embedded systems. Some of the assumptions used by the existing analysis may not be strictly followed by some legacy tools due to optimizations applied during the development of these systems. As a result, the existing analysis may not be applicable in some cases. In this paper we identify one such case. That is, the case in which all the tasks in a multi-rate task chain have equal priorities despite the fact that they have different periods. Furthermore, the chain contains at least one single-rate sub-chain. We also propose a preliminary solution that makes the existing analysis applicable to this case. However, the proposed solution is pessimistic. Currently, we are working on minimizing the pessimism.

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