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Application-Level Evaluation of IEEE 802.1AS Synchronized time and Linux for distributed real-time systems

ACM TRANSACTIONS ON EMBEDDED COMPUTING systems 2025年第1期24卷 1-16页

作者： Tijero, Hector perez Gutierrez Garcia, J. javier Prieto, D. I. E. G. O. GARCiA Univ Cantabria Santander Cantabria Spain

The use of Ethernet and Linux is becoming common in industrial applications, even for those with real-time requirements, although neither of them were originally designed for this purpose. The emergence of Industry 4.0 (also known as Industrial Internet of Things, IIoT) has encouraged the evolution of these technologies to better handle real-time issues. On the one hand, Linux now supports mechanisms to configure certain real-time parameters, as well as core isolation and interrupt allocation facilities in multicore processors. On the other hand, the set of Ethernet standards IEEE 802.1 time-Sensitive Networking (TSN) includes a high precision clock synchronization protocol (IEEE 802.1AS). The purpose of this work is to outline an execution framework for distributed systems based on TSN and Linux, which allows the execution of time-aware applications. We have studied and evaluated different configurations available for the proposed execution framework. In particular, a detailed characterization of the clock synchronization mechanism, from the application point of view, has been performed. Some conclusions about the current real-time capabilities of these technologies are also presented.

关键词： Clock synchronization distributed real-time systems IEEE 802.1AS Linux TSN Industry 4.0

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distributed real-time systems FOR MANUFACTURING AUTOMATION

DISTRIBUTED REAL-TIME SYSTEMS FOR MANUFACTURING AUTOMATION

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SYMP ON INTELLIGENT COMPONENTS AND INSTRUMENTS FOR CONTROL APPLICATIONS

作者： RZEHAK, H

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Formal patterns for multirate distributed real-time systems

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SCIENCE OF COMPUTER PROGRAMMING 2014年第PART A期91卷 3-44页

作者： Bae, Kyungmin Meseguer, Jose Olveczky, Peter Csaba Univ Illinois Champaign IL 61820 USA Univ Oslo N-0316 Oslo Norway

distributed real-time systems (DRTSs), such as avionics and automotive systems, are very hard to design and verify. Besides the difficulties of asynchrony, clock skews, and network delays, an additional source of complexity comes from the multirate nature of many such systems, which must implement several levels of hierarchical control at different rates. In previous work we showed how the design and implementation of a single-rate DRTS which should behave in a virtually synchronous way can be drastically simplified by the PALS model transformation that generates the DRTS from a much simpler synchronous model. In this work we present several simple model transformations and a multirate extension of the PALS pattern which can be combined to reduce the design and verification of a virtually synchronous multirate DRTS to the much simpler task of specifying and verifying a single synchronous system. We illustrate the ideas with a multirate hierarchical control system where a central controller orchestrates control systems in the ailerons and tail of an airplane to perform turning maneuvers. (C) 2013 Elsevier B.V. All rights reserved.

关键词： distributed real-time systems Multirate systems Synchronizers Model checking Rewriting logic

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Network conscious design of distributed real-time systems

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JOURNAL OF systems ARCHITECTURE 1998年第2期45卷 131-156页

作者： Park, JW Kim, YS Hong, SS Saksena, M Noh, SH Kwon, WH Seoul Natl Univ Sch Elect Engn Seoul 151742 South Korea Seoul Natl Univ ACI ERC Autom Syst Res Inst Seoul 151742 South Korea Concordia Univ Dept Comp Sci Montreal PQ H3G 1M8 Canada Hongik Univ Dept Comp Engn Seoul 121791 South Korea

In this paper, we present a network conscious approach to designing distributed real-time systems. Given a task graph design of the system, the end-to-end constraints on the inputs and outputs, and the task allocation on a given distributed platform, we automatically generate task attributes (e.g., periods and deadlines) such that (i) the task set is schedulable, and (ii) the end-to-end constraints are satisfied. The method works by first transforming the end-to-end constraints into a set of intermediate constraints on task attributes, and then solving the intermediate constraints. The complexity of constraint solving is tackled by reducing the problem into more tractable parts, and then solving each subproblem using heuristics to enhance schedulability. The methodology presented in this process can be mostly automated, and provides useful feedback to a designer when it fails to find a solution. We expect that the techniques presented in this paper will help reduce the laborious process of designing a real-time system, by bringing resource contention and schedulability aspects early into the design process. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： distributed real-time systems design methodology real-time network constraint solving nonlinear optimization real-time scheduling control system

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ANALYTIC MODELS OF ADAPTIVE LOAD SHARING SCHEMES IN distributed real-time systems

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IEEE TRANSACTIONS ON PARALLEL AND distributed systems 1993年第7期4卷 740-761页

作者： SHIN, KG HOU, CJ Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

In a distributed real-time system, nonuniform task arrivals may temporarily overload some nodes while leaving some other nodes idle. As a result, some of the tasks on an overloaded node may miss their deadlines even if the overall system has the capacity to meet the deadlines of all tasks. In a companion paper [1], we proposed, without any modeling analysis, a decentralized, dynamic load sharing (LS) scheme as a solution to this problem. In this paper, we develop analytic queueing models to comparatively evaluate the proposed LS scheme as well as three other schemes: no LS, LS with random selection of a receiver node, and LS with perfect information. The evolution of a node's load state is modeled as a continuous-time semi-Markov process, where cumulative execution time (CET), rather than the commonly-used queue length (QL), is employed to describe the workload of a node. Not only fundamental differences among the different LS schemes are addressed in the analytic models, but also implementation overheads are taken into account Several metrics relevant to real-time performance are derived from these models: in particular, we evaluate the probability of a task missing its deadline, called the probability of dynamic failure. The proposed scheme is compared against other LS schemes using these performance metrics. The validity of analytic models is checked with simulations. Both analytic and simulation results indicate that by using judicious exchange/use of state information and Bayesian decision mechanism, the proposed scheme makes a significant improvement over other existing LS schemes in minimizing the probability of dynamic failure.

关键词： BAYESIAN ANALYSIS CONTINUOUS-time MARKOV CHAINS DEADLINES distributed real-time systems LOAD SHARING LOCATION AND TRANSFER POLICIES PERFORMANCE EVALUATION RANDOM PROBING AND SELECTION

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JMC: Jitter-Based Mixed-Criticality Scheduling for distributed real-time systems

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IEEE INTERNET OF THINGS JOURNAL 2019年第4期6卷 6310-6324页

作者： Lee, Kilho Kim, Minsu Kim, Hayeon Chwa, Hoon Sung Lee, Jaewoo Lee, Jinkyu Shin, Insik Korea Adv Inst Sci & Technol Sch Comp Daejeon 34141 South Korea DGIST Dept Informat & Commun Engn Daegu 42988 South Korea Chung Ang Univ Dept Ind Secur Seoul 06974 South Korea Sungkyunkwan Univ Dept Comp Sci & Engn Suwon 16419 South Korea

These days, the term of Internet of Things (IoT) becomes popular to interact and cooperate with individual smart objects, and one of the most critical challenges for IoT is to achieve efficient resource sharing as well as ensure safetystringent timing constraints. To design such reliable real-time IoT, this paper focuses on the concept of mixed-criticality (MC) introduced to address the low processor utilization on traditional real-time systems. Although different worst-case execution time estimates depending on criticality are proven effective on processor scheduling, the MC concept is not yet mature on distributed systems (such as IoT), especially with end-to-end deadline guarantee. To the best of our knowledge, this paper presents the first attempt to apply the MC concept into interference (or jitter), which is a complicated source of pessimism when analyzing the schedulability of distributed systems. Our goal is to guarantee the end-to-end deadlines of high-criticality flows and minimize the deadline miss ratio of low-criticality flows in distributed systems. To achieve this goal, we introduce a jitter-based MC (JMC) scheduling framework, which supports node-level mode changes in distributed systems. We present an optimal feasibility condition (subject to given schedulability analysis) and two policies to determine jitter-threshold values to achieve the goal in different conditions. Via simulation results for randomly generated workloads, JMC outperforms an existing criticality-monotonic scheme in terms of achieving higher schedulability and fewer deadline misses.

关键词： distributed real-time systems end-to-end dead-line guarantee jitter-based mixed-criticality (JMC) scheduling worst-case response time

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Testing distributed real-time systems

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MICROPROCESSORS AND MICROsystems 2001年第9期24卷 463-478页

作者： Thane, H Hansson, H Malardalen Univ Malardalen Real Time Res Ctr Dept Comp Engn S-72123 Vasteras Sweden

For testing of sequential software it is usually sufficient to provide the same input land program state) in order to reproduce the output. For real-time systems (RTS), on the other hand, we need also to control, or observe, the timing and order of the inputs. If the system additionally is multitasking, we also need to take timing and the concurrency of the executing tasks into account. In this paper we present a method for deterministic testing of multitasking RTS, which allows explorative investigations of real-time system behavior. The method includes an analysis technique that given a set of tasks and a schedule derives all execution orderings that can occur during run-time. These orderings correspond to the possible inter-leavings of the executing tasks. The method also includes a testing strategy that using the derived execution orderings can achieve deterministic, and even reproducible, testing of RTS. Since, each execution ordering can be regarded as a sequential program, it becomes possible to use techniques for testing of sequential software in testing multitasking real-time system software. We also show how this analysis and testing strategy can be extended to encompass distributed computations, communication latencies and the effects of global clock synchronization. The number of execution orderings is an objective measure of the testability of a system since it indicates how many behaviors the system can exhibit during runtime. In the pursuit of finding errors we must thus cover all these execution orderings. The fewer the orderings the better the testability. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： determinism testing distributed real-time systems reproducibility

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The RTDEVS/CORBA environment for simulation-based design of distributed real-time systems

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SIMULATION-TRANSACTIONS OF THE SOCIETY FOR MODELING AND SIMULATION INTERNATIONAL 2003年第4期79卷 197-210页

作者： Cho, YK Hu, XL Zeigler, BP Republ Korea Air Force Nonsan City 320913 Choongnam South Korea Univ Arizona Dept Elect & Comp Engn Arizona Ctr Integrat Modeling & Simulat Tucson AZ 85721 USA

The increasing complexity of large-scale distributed real-time systems demands powerful real-time object computing technologies. Furthermore, systematic design approaches are needed to support analysis, design, test, and implementation of these systems. The authors discuss RTDEVS/CORBA, an implementation of discrete event system specification (DEVS) modeling and simulation theory based on real-time CORBA communication middleware. With RTDEVS/CORBA, the software model of a complex distributed real-time system can be designed and then tested in a virtual testing environment and finally executed in a real distributed environment. This model continuity and simulation-based design approach effectively manages software complexity and consistency problems for complex systems, increases the flexibility for test configurations, and reduces the time and cost for testing. The layered architecture and different implementation issues of RTDEVS/CORBA are studied and discussed. An example application is then given to show how RTDEVS/CORBA supports a framework for model continuity in distributed real-time modeling and simulation.

关键词： distributed real-time systems modeling and simulation DEVS CORBA model continuity simulation-based design virtual testing environment

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Modeling distributed real-time systems in TIOA and UPPAAL

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ACM TRANSACTIONS ON EMBEDDED COMPUTING systems 2016年第1期16卷 1–26页

作者： Kartal, Yusuf Bora Schmidt, Ece Guran Schmidt, Klaus Werner Middle East Tech Univ Dept Elect & Elect Engn Dumlupinar Bulvari 1 TR-06800 Cankaya Turkey Cankaya Univ Dept Mechatron Engn Mahallesi Mimar Sinan Caddesi 4 TR-06790 Etimesgut Ankara Turkey

The mission- and life-critical properties of distributed real-time systems require concurrent modeling, analysis, and formal verification in the design stage. The timed input/output automata (TIOA) framework and the UPPAAL software package are two widely used modeling and verification tools for this purpose. To this end, we develop the algorithm TUConvert for converting distributed TIOA models to UPPAAL behavioral models and formally prove its correctness. We demonstrate the applicability of our algorithm by the formal verification of a distributed real-time industrial communication protocol that is modeled by TIOA.

关键词： distributed real-time systems timed input/output automata UPPAAL formal verification

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Model continuity in the design of dynamic distributed real-time systems

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IEEE TRANSACTIONS ON systems MAN AND CYBERNETICS PART A-systems AND HUMANS 2005年第6期35卷 867-878页

作者： Hu, XL Zeigler, BP Georgia State Univ Dept Comp Sci Atlanta GA 30303 USA Univ Arizona Arizona Ctr Integrat Modeling & Simulat Elect & Comp Engn Dept Tucson AZ 85721 USA

Model continuity refers to the ability to transition as much as possible a model specification through the stages of a development process. In this paper, the authors show how a modeling and simulation environment, based on the discrete event system specification formalism, can support model continuity in the design of dynamic distributed real-time systems. In designing such systems, the authors restrict such continuity to the models that implement the system's real-time control and dynamic reconfiguration. The proposed methodology supports systematic modeling of dynamic systems and adopts simulation-based tests for distributed real-time software. Model continuity is emphasized during the entire process of software development-the control models of a dynamic distributed real-time system can be designed, analyzed, and tested by simulation methods, and then smoothly transitioned from simulation to distributed execution. A dynamic team formation distributed robotic system is presented as an example to show how model continuity methodology effectively manages the complexity of developing and testing the control software for this system.

关键词： discrete event system specification (DEVS) distributed real-time systems dynamic reconfiguration model continuity modeling and simulation robotic team formation

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