[1989] Proceedings. Real-Time Systems Symposium

5-7 Dec. 1989

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Displaying Results 1 - 25 of 37
  • Minimizing mean flow time with error constraint

    Publication Year: 1989, Page(s):2 - 11
    Cited by:  Papers (7)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (719 KB)

    In a new model of task systems studied by J.W.S. Liu et al. (1987) each task is logically decomposed into two subtasks, mandatory and optional. The authors discuss preemptively scheduling this kind of task system on p>or=1 identical processors so as to minimize the mean flow time. Given a task system and an error threshold K, the goal is to find a preemptive schedule such that each task is exec... View full abstract»

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  • Fast algorithms for scheduling imprecise computations

    Publication Year: 1989, Page(s):12 - 19
    Cited by:  Papers (24)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (569 KB)

    Consideration is given to the problem of scheduling tasks each of which is logically decomposed into a mandatory subtask and an optional subtask. The mandatory subtask must be executed to completion. If the available processor time is insufficient, the optional subtask can be left incomplete. The error in the result of a task is equal to the processing time of the unfinished portion of the optiona... View full abstract»

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  • Events: a structuring mechanism for a real-time runtime system

    Publication Year: 1989, Page(s):22 - 30
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (588 KB)

    Recent progress in the implementation of the ORE real-time programming language is reported. A summary of the important features of the language is included. Progress in designing a runtime system for the language is reported. The design issues are discussed. A model of ORE processes is described. The set of operations defined on events, strips, and processes is described. Examples of the implemen... View full abstract»

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  • Toward the deterministic scheduling of Ada tasks

    Publication Year: 1989, Page(s):31 - 40
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (853 KB)

    Addresses the problem of scheduling a restricted form of Ada tasks so as to guarantee satisfaction of timing constraints. Specifically, the use of deterministic scheduling for periodic tasks communicating through rendezvous is studied. This extends the work of A.K. Mok (1984) scheduling deterministic rendezvous to a class of nondeterministic rendezvous constructs. A state-space approach is used to... View full abstract»

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  • A distributed real-time language and its operational semantics

    Publication Year: 1989, Page(s):41 - 50
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (943 KB)

    An important issue in real-time computing is the development of a sufficiently abstract computational model. This model must enable one to specify, analyze, and implement distributed real-time systems. Therefore, there must also be a programming language based on the model. A description is given of such a programming language and its operational semantics. In the design of the language the applic... View full abstract»

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  • Nearly Poisson transfer traffic in real-time networks

    Publication Year: 1989, Page(s):52 - 58
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (434 KB)

    Consideration is given to a homogeneous distributed network of nodes with a quasi-dynamic random task-sharing discipline and identical Poisson hard real-time traffic at each node. The task-sharing discipline under consideration permits tasks to be shared randomly around the network as long as remaining task laxity permits. Analysis of task loss in such a network requires the assumption that the tr... View full abstract»

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  • Scheduling parallelizable jobs on multiprocessors

    Publication Year: 1989, Page(s):59 - 67
    Cited by:  Papers (18)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (553 KB)

    The effect of parallel execution on the complexity of scheduling hard real time jobs on multiprocessors is analyzed. Studied is the scheduling problem in which a job may be parallelized and executed on any number of processors concurrently. In hard real-time systems, each job must be completed before a deadline. Parallelization gives a scheduler the flexibility to allocate more processors to a job... View full abstract»

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  • Communicating shared resources: a model for distributed real-time systems

    Publication Year: 1989, Page(s):68 - 78
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (866 KB)

    A real-time formalism called communicating shared resources (CSR) is presented. CSR consists of a programming language that allows the explicit expression of timing constraints and resources, and a computation model that resolves resource contention based on event priority. A full denotational semantics is provided for the programming language, grounded in a resource-based computation model. To il... View full abstract»

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  • Token-ring adapter-chipset architectural considerations for real-time systems

    Publication Year: 1989, Page(s):79 - 90
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (952 KB)

    The results of implementation studies utilizing commercially available IEEE 802.5 chip sets and boards are reported. Serious implementation flaws were discovered that prevent the full potential of the IEEE 802.5 token ring standard from being realized for real-time applications. Specifically, unbounded delays can be introduced which not only destroy the desired response time determinism offered by... View full abstract»

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  • Real-time temporal logic decision procedures

    Publication Year: 1989, Page(s):92 - 101
    Cited by:  Papers (7)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (805 KB)

    Real-time systems are modeled by a timed transition model (TTM). For any finite-state TTM, decision procedures are provided for checking a small but important class of properties, which are specified in real-time temporal logic. The procedures are linear in the size of the system reachability graph. The class of properties includes invariance, precedence, eventuality, and real-time response specif... View full abstract»

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  • A framework for reasoning about time and reliability

    Publication Year: 1989, Page(s):102 - 111
    Cited by:  Papers (24)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (585 KB)

    A logic is presented for stating properties such as 'after a request for service there is at least a 98% probability that the service will be carried out within 2 s'. The logic extends the temporal logic CTL by E.A. Emerson et al. (1983) with time and probabilities. Formulas are interpreted over discrete time Markov chains. Algorithms are provided for checking that a given Markov chain satisfies a... View full abstract»

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  • A transformational method for verifying safety properties in real-time systems

    Publication Year: 1989, Page(s):112 - 123
    Cited by:  Papers (8)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (888 KB)

    A two-step method is presented for verifying that safety properties are not violated by an HMS (hierarchical multistate) specification of a system. In the first step, the question of safety verification is recast as a reachability problem in an extension of the HMS machine. In the second step, reachability is determined by the use of correctness-preserving and partial correctness-preserving transf... View full abstract»

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  • Transient overloads in fault-tolerant real-time systems

    Publication Year: 1989, Page(s):126 - 133
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (529 KB)

    A novel technique that allows a single system to guarantee the execution of both periodic and aperiodic tasks within hard deadlines is presented. The approach is based on dynamically changing the replication factor of periodic tasks in response to aperiodic tasks. The technique is directly applicable to the problem of transient overloads that are time-critical. Preliminary results that show the ap... View full abstract»

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  • Algorithm-based error detection for signal processing applications on a hypercube multiprocessor

    Publication Year: 1989, Page(s):134 - 143
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (713 KB)

    In many cases, it may be possible to redesign parallel algorithms so as to provide a low-cost online scheme for hardware error detection without any hardware modifications. This approach is called algorithm-based error detection. Two useful computations in signal processing are analyzed: QR factorization and singular-value decomposition. For each of these applications, numerous ways of applying al... View full abstract»

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  • Experimental evaluation of real-time transaction processing

    Publication Year: 1989, Page(s):144 - 153
    Cited by:  Papers (55)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (765 KB)

    Results are presented of empirical evaluations carried out on the RT-CARAT testbed. This testbed was used evaluating a set of integrated protocols that support real-time transactions. A basic locking scheme for concurrency control was used to develop and evaluate several algorithms for handling CPU scheduling, data-conflict resolution, deadlock resolution, transaction wakeup, and transaction resta... View full abstract»

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  • Performance analysis of FCFS and improved FCFS scheduling algorithms for dynamic real-time computer systems

    Publication Year: 1989, Page(s):156 - 165
    Cited by:  Papers (24)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (672 KB)

    A study is made of the performance of FCFS (first-come, first-served) and improved FCFS scheduling algorithms for dynamic real-time computer systems in which tasks arrive as a random process and each task has a laxity specifying the maximum time a task can wait for the service. The general solution for M/M/1 systems in which the FCFS or an improved FCFS scheduling algorithm is used is obtained. In... View full abstract»

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  • The rate monotonic scheduling algorithm: exact characterization and average case behavior

    Publication Year: 1989, Page(s):166 - 171
    Cited by:  Papers (582)  |  Patents (8)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (481 KB)

    An exact characterization of the ability of the rate monotonic scheduling algorithm to meet the deadlines of a periodic task set is represented. In addition, a stochastic analysis which gives the probability distribution of the breakdown utilization of randomly generated task sets is presented. It is shown that as the task set size increases, the task computation times become of little importance,... View full abstract»

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  • Application of real-time monitoring to scheduling tasks with random execution times

    Publication Year: 1989, Page(s):172 - 181
    Cited by:  Papers (10)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (748 KB)

    A real-time monitor is employed to aid in scheduling tasks with random execution times in a real-time computing system. Scheduling algorithms are usually based on the worst-case execution time (WET) of each task. Due to data-dependent loops and conditional branches in each program and resource-sharing delay during execution, this WET is usually difficult to obtain and could be several orders of ma... View full abstract»

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  • Signal processor architecture for high-performance real-time applications

    Publication Year: 1989, Page(s):184 - 193
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1062 KB)

    A description is given of the software environment for SPARTA (signal processor architecture for real-time applications). The SPARTA hardware consists of a hybrid system with three different types of computers. The program development environment includes the PLH high-level language (on an IBM VM/CMS mainframe) for generating efficient real-time signal processor code. The runtime (user) interface ... View full abstract»

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  • Object-oriented design of real-time software

    Publication Year: 1989, Page(s):194 - 201
    Cited by:  Papers (20)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (665 KB)

    An examination is made of the ability of the object-oriented model to represent and encapsulate the temporal characteristics of adaptable, real-time software. The differences between object-oriented design and the more traditional function-oriented design of real-time systems are briefly reviewed. The various temporal characteristics present in a real-time, object-oriented system and techniques fo... View full abstract»

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  • A framework for specification and design of software for advanced sensor systems

    Publication Year: 1989, Page(s):204 - 213
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (798 KB)

    An investigation is presented of the relationship between external inputs and the demands imposed on the various resources in advanced sensor systems. This reveals the deficiency of the classical execution model for hard real-time systems, consisting of periodic and sporadic tasks, for modeling the workload in such systems. The classical model is extended with additional attributes for describing ... View full abstract»

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  • A distributed fault tolerant architecture for nuclear reactor control and safety functions

    Publication Year: 1989, Page(s):214 - 221
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (621 KB)

    A fault-tolerant architecture that provides tolerance to a broad scope of hardware, software, and communications faults is being developed. This architecture relies on widely available commercial operating systems, local area networks, and software standards. Thus development time is significantly shortened, and modularity allows for continuous and inexpensive system enhancement throughout the exp... View full abstract»

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  • A fault-tolerant microcomputer for advanced control: architecture and performability analysis

    Publication Year: 1989, Page(s):222 - 228
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (394 KB)

    The hardware and software architecture of a fault-tolerant microcomputer for advanced control is presented. Use is made of performability as a performance and reliability measure. It is computed by means of the aggregation/decomposition technique with the aid of a numerical algorithm. An analysis is made of the influence of certain types of faults (i.e. permanent, intermittent, and transient) on t... View full abstract»

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  • SMART (strategic memory allocation for real-time) cache design

    Publication Year: 1989, Page(s):229 - 237
    Cited by:  Papers (78)  |  Patents (17)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (804 KB)

    A discussion is presented as to why the present approach to cache architecture design results in unpredictable performance improvements in real-time systems with priority-based preemptive scheduling algorithms. The SMART cache design is shown to be compatible with the goals of scheduling in a real-time system. The results of this research provide a scheme not only for utilizing the performance enh... View full abstract»

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  • A decomposition approach to non-preemptive scheduling in hard real-time systems

    Publication Year: 1989, Page(s):240 - 248
    Cited by:  Papers (2)  |  Patents (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (409 KB)

    It is well known that the optimal nonpreemptive scheduling of n tasks on a single processor requires a number of operations proportional to the factorial of the number of tasks. It is proposed that tasks be scheduled in two steps. In the first step a sequence for the tasks is generated, and in the second step the tasks are bounded in time according to the selected sequence by assigning a start tim... View full abstract»

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