Proceedings 16th IEEE Real-Time Systems Symposium

5-7 Dec. 1995

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  • Proceedings 16th IEEE Real-Time Systems Symposium [front matter]

    Publication Year: 1995, Page(s):iii - vii
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    Freely Available from IEEE
  • Proving dynamic properties in an aerospace application

    Publication Year: 1995, Page(s):2 - 10
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (689 KB)

    We give an exposition to an ongoing research effort in cooperation with aerospace industries in Sweden. We report on an application of formal verification techniques on a landing gear system. This system consists of actuating hydromechanic and electromechanic hardware, and of controlling software components. We emphasize the need for modelling techniques and languages covering the whole spectrum f... View full abstract»

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  • Modelling a real time control system based on distributed objects

    Publication Year: 1995, Page(s):11 - 15
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    The CERN Research and Development project (RD-38), named CICERO, aims to identify and design the main building blocks of a generic control information system based on distributed objects. The project is producing an integrating framework (named Cortex) into which user real-time control objects will ultimately be plugged (and played) and a control information system to support its configuration and... View full abstract»

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  • A scalable real-time synchronization protocol for distributed systems

    Publication Year: 1995, Page(s):18 - 27
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1110 KB)

    A distributed protocol is proposed for the synchronization of real-time tasks that have variable resource requirements. The protocol is simple to implement and is intended for large-scale distributed or parallel systems in which processes communicate by message passing. Critical sections, even when nested, may be executed on any processor. Thus, given an adequate number of processors, the executio... View full abstract»

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  • Real-time computing with lock-free shared objects

    Publication Year: 1995, Page(s):28 - 37
    Cited by:  Papers (21)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1111 KB)

    This paper considers the use of lock-free shared objects within hard real-time systems. As the name suggests, lock-free shared objects are distinguished by the fact that they are not locked. As such, they do not give rise to priority inversions, a key advantage over conventional, lock-based object-sharing approaches. Despite this advantage, it is not immediately apparent that lock-free shared obje... View full abstract»

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  • Kernel-level threads for dynamic, hard real-time environments

    Publication Year: 1995, Page(s):38 - 48
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1141 KB)

    The design of a kernel-level thread package for dynamic, hard real-time environments is presented. A highly integrated design is used to ensure predictability. A system description language and real-time programming language are used to specify key properties of threads and thread groups. For a thread, this includes whether or not the thread spawns other threads at run-time, the type of performanc... View full abstract»

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  • MiThOS-a real-time micro-kernel threads operating system

    Publication Year: 1995, Page(s):49 - 53
    Cited by:  Papers (4)  |  Patents (18)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (585 KB)

    MiThOS (Micro-kernel Threads Operating System) is an experimental operating system for embedded systems. The system kernel is a first implementation of the POSIX Minimal Real-Time System Profile. It is based on prior work of a library implementation of Pthreads (POSIX threads). The system is fully preemptive. It supports multi-threading within a single process environment with shared kernel and us... View full abstract»

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  • HYTECH: the next generation

    Publication Year: 1995, Page(s):56 - 65
    Cited by:  Papers (64)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1272 KB)

    We describe a new implementation of HYTECH, a symbolic model checker for hybrid systems. Given a parametric description of an embedded system as a collection of communicating automata, HYTECH automatically computes the conditions on the parameters under which the system satisfies its safety and timing requirements. While the original HYTECH prototype was based on the symbolic algebra tool Mathemat... View full abstract»

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  • Two examples of verification of multirate timed automata with Kronos

    Publication Year: 1995, Page(s):66 - 75
    Cited by:  Papers (33)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (875 KB)

    Multirate timed automata are an extension of timed automata where each clock has its own speed varying between a lower and an upper bound that may change from one control location to another. This formalism is well-suited for specifying hybrid systems where the dynamics of the continuous variables are defined or can be approximated by giving the minimal and maximal rate of change. To avoid the dif... View full abstract»

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  • Compositional and symbolic model-checking of real-time systems

    Publication Year: 1995, Page(s):76 - 87
    Cited by:  Papers (48)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1148 KB)

    Efficient automatic model-checking algorithms for real-time systems have been obtained in recent years based on the state-region graph technique of Alur, Courcoubetis and Dill (1990). However, these algorithms are faced with two potential types of explosion arising from parallel composition: explosion in the space of control nodes, and explosion in the region space over clock-variables. In this pa... View full abstract»

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  • Value vs. deadline scheduling in overload conditions

    Publication Year: 1995, Page(s):90 - 99
    Cited by:  Papers (49)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (795 KB)

    We present a comparative study among scheduling algorithms which use different priority assignments and different guarantee mechanisms to improve the performance of a real-time system during overload conditions. In order to enhance the quality of service, we assume that tasks are characterized not only by a deadline, but also by an importance value. The performance of the scheduling algorithm is t... View full abstract»

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  • Dual priority scheduling

    Publication Year: 1995, Page(s):100 - 109
    Cited by:  Papers (62)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (792 KB)

    In this paper, we present a new strategy for scheduling tasks with soft deadlines in real-time systems containing periodic, sporadic and adaptive tasks with hard deadlines. In such systems, much of the spare capacity present is due to sporadic and adaptive tasks not arriving at their maximum rate. Offline methods of identifying spare capacity such as the Deferrable Server or Priority Exchange Algo... View full abstract»

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  • Skip-Over: algorithms and complexity for overloaded systems that allow skips

    Publication Year: 1995, Page(s):110 - 117
    Cited by:  Papers (109)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (689 KB)

    In applications ranging from video reception to telecommunications and packet communication to aircraft control, tasks enter periodically and have fixed response time constraints, but missing a deadline is acceptable, provided most deadlines are met. We call such tasks "occasionally skippable". We look at the problem of uniprocessor scheduling of occasionally skippable periodic tasks in an environ... View full abstract»

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  • Enhancing real-time schedules to tolerate transient faults

    Publication Year: 1995, Page(s):120 - 129
    Cited by:  Papers (31)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (976 KB)

    We present a scheme to guarantee that the execution of real-time tasks can tolerate transient and intermittent faults assuming any queue-based scheduling technique. The scheme is based on reserving sufficient slack: in a schedule such that a task can be re-executed before its deadline without compromising guarantees given to other tasks. Only enough slack is reserved in the schedule to guarantee f... View full abstract»

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  • A software fault injection tool on real-time Mach

    Publication Year: 1995, Page(s):130 - 140
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1287 KB)

    Ensuring that a distributed real-time system with strict dependability constraints meets its prescribed specification is a growing challenge that confronts software developers and system engineers. This paper reports on a software fault injection tool, called SockPFI, for testing the fault tolerance and timing behavior of distributed real-time applications. SockPFI, developed on Real-Time Mach, ca... View full abstract»

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  • Fault-tolerant real-time communication in FDDI-based networks

    Publication Year: 1995, Page(s):141 - 150
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1072 KB)

    FDDI-Based Reconfigurable Networks have an architecture that is suitable for delivering messages that have hard real-time constraints as well as certain fault-tolerance requirements. This architecture uses multiple FDDI networks to connect hosts and provides for automatic reconfiguration to maintain high network bandwidth in spite of faults. An important open problem is how resources in such netwo... View full abstract»

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  • Joint scheduling of distributed complex periodic and hard aperiodic tasks in statically scheduled systems

    Publication Year: 1995, Page(s):152 - 161
    Cited by:  Papers (62)  |  Patents (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (900 KB)

    In this paper we present algorithms for the joint scheduling of periodic and aperiodic tasks in statically scheduled distributed real-time systems. Periodic tasks are precedence constrained, distributed, and communicating over the nodes of the systems. Both soft and hard aperiodic tasks are handled. After a static schedule has been created in a first step, the algorithms determine the amount and d... View full abstract»

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  • Optimal combined task and message scheduling in distributed real-time systems

    Publication Year: 1995, Page(s):162 - 171
    Cited by:  Papers (15)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1003 KB)

    In this paper we present a branch-and-bound (B&B) algorithm for combined task and message scheduling in distributed hard real-time systems. The algorithm finds an optimal schedule for a set of communicating tasks with known arrival times, precedence constraints, and resource requirements in conjunction with the assignment and scheduling of intertask messages over communication links. The sched... View full abstract»

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  • Distributed pinwheel scheduling with end-to-end timing constraints

    Publication Year: 1995, Page(s):172 - 181
    Cited by:  Papers (19)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (888 KB)

    Algorithms for allocating resources and scheduling tasks are important to the success of many real-time systems with end-to-end performance requirements. In this paper, an end-to-end scheduling model based on the pinwheel scheduling algorithms is presented for distributed real-time systems. We discuss how tasks on different nodes may be transformed to have harmonic periods. We also present algorit... View full abstract»

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  • The design of large real-time systems: the time-triggered approach

    Publication Year: 1995, Page(s):182 - 187
    Cited by:  Papers (10)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (660 KB)

    The time-triggered (TT) architecture approach supports the spatial partitioning of a large, distributed real-time system into a set of autonomous subsystems with small control-free data-sharing interfaces between them. This paper presents such a TT architecture and gives a detailed description of the interface between an autonomous time-triggered communication subsystem based on the TTP protocol a... View full abstract»

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  • Applicability of simulated annealing methods to real-time scheduling and jitter control

    Publication Year: 1995, Page(s):190 - 199
    Cited by:  Papers (18)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1048 KB)

    This paper presents a non-conventional scheduling approach for distributed static systems where tasks are periodic and have arbitrary deadlines, precedence, and exclusion constraints. The solution presented in this work not only creates feasible schedules, but also minimizes jitter for periodic tasks. The problem of scheduling real-time tasks with minimum jitter is particularly important in many c... View full abstract»

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  • Fairness in periodic real-time scheduling

    Publication Year: 1995, Page(s):200 - 209
    Cited by:  Papers (17)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (894 KB)

    The issue of temporal fairness in periodic real-time scheduling is considered. It is argued that such fairness is often a desirable characteristic in real-time schedules. A concrete criterion for temporal fairness-pfairness-is described. The weight-monotonic scheduling algorithm, a static priority scheduling algorithm for generating pfair schedules, is presented and proven correct. A feasibility t... View full abstract»

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  • Robust aperiodic scheduling under dynamic priority systems

    Publication Year: 1995, Page(s):210 - 219
    Cited by:  Papers (52)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (950 KB)

    When hard periodic and firm aperiodic tasks are jointly scheduled in the same system, the processor workload can vary according to the arrival times of aperiodic requests. In order to guarantee the schedulability of the periodic task set, in overload conditions some aperiodic tasks must be rejected. In this paper we propose a technique that, in overload conditions, adds robustness to the joint sch... View full abstract»

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  • On slot reuse for isochronous services in DQDB networks

    Publication Year: 1995, Page(s):222 - 231
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1126 KB)

    DQDB is a MAC protocol jointly adopted by IEEE and ANSI as the candidate protocol for MANs, and has been studied by many researchers. Previously, we laid a formal basis for guaranteeing the timely delivery of isochronous (real-time) messages with hard deadlines, and devised a slot allocation scheme for allocating pre-arbitrated (PA) slots to isochronous message streams in DQDB networks. In this pa... View full abstract»

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  • Dynamic real-time channel setup and tear-down in DQDB networks

    Publication Year: 1995, Page(s):232 - 241
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1091 KB)

    The distributed queue dual bus (DQDB) protocol has been jointly adopted by IEEE and ANSI as a standard (IEEE802.6) for metropolitan area networks (MANs). As such, how to provide various services in the DQDB protocol has attracted increasing attention. In particular, how to guarantee the timely delivery of isochronous (real-time) messages with hard deadline constraints is one of the open issues yet... View full abstract»

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