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[1990] Proceedings 11th Real-Time Systems Symposium

5-7 Dec. 1990

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Displaying Results 1 - 25 of 34
  • Proceedings. 11th Real-Time Systems Symposium (Cat. No.90CH2933-0)

    Publication Year: 1990
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    Freely Available from IEEE
  • The ARTS real-time object model

    Publication Year: 1990, Page(s):2 - 10
    Cited by:  Papers (19)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (857 KB)

    The authors present the motivation for using an object model for real-time operating systems, and describe the object model used in the ARTS kernel. A discussion is presented of the novel object classification and the priority inheritance properties which arise from this taxonomy. Various methods for implementing critical regions are described, and some guidelines as to the use of each are given.&... View full abstract»

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  • Time capsules: an abstraction for access to continuous-media data

    Publication Year: 1990, Page(s):11 - 20
    Cited by:  Papers (12)  |  Patents (6)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1045 KB)

    The author presents the time capsule abstraction to describe how timed data shall be stored, exchanged, and accessed in a real-time system. When data are written into a time capsule, a time stamp and a duration are associated with the data item. When it is read, a time stamp is used to select the data item. The time capsule abstraction includes the notion of clocks that ensure periodic data access... View full abstract»

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  • Incremental garbage collection of concurrent objects for real-time applications

    Publication Year: 1990, Page(s):21 - 30
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (789 KB)

    The authors show how to perform real-time automatic garbage collection of objects possessing their own thread of control. Beyond its interest as a novel real-time problem, the relevance of automatic management and concurrent objects to real-time applications is briefly discussed. The specific model of concurrent objects used in the paper is explained. A definition of real-time garbage collection i... View full abstract»

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  • Minimizing the number of late tasks with error constraint

    Publication Year: 1990, Page(s):32 - 40
    Cited by:  Papers (4)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (860 KB)

    The problem of minimizing the number of late tasks in the imprecise computation model is considered. Each task consists of two subtasks, mandatory and optional. A task is said to be on-time if its mandatory part is completed by its deadline; otherwise, it is said to be late. An on-time task incurs an error if its optional part is not computed by the deadline, and the error is simply the execution ... View full abstract»

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  • Resource reclaiming in real time

    Publication Year: 1990, Page(s):41 - 50
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (964 KB)

    Resource reclaiming refers to the problem of utilizing the resources left unused by a task when it executes in less than its worst-case computation time, or when a task is deleted from the current schedule. In dynamic real-time multiprocessor environments, resource reclaiming can be used to improve the average performance. Dynamic resource reclaiming algorithms must be effective in reclaiming unus... View full abstract»

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  • Scalability of a distributed real-time resource counter

    Publication Year: 1990, Page(s):51 - 59
    Cited by:  Papers (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (778 KB)

    The authors address the topic of how to meet a real-time constraint as the load on a distributed system increases, without increasing the capacity of the individual processors. The application studied is a real-time resource counter with a probabilistic correctness criterion, and is motivated by the problem of implementing resource management in the telephone network. They introduce a model that c... View full abstract»

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  • Implementing a verifier for real-time systems

    Publication Year: 1990, Page(s):62 - 71
    Cited by:  Papers (13)  |  Patents (2)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1008 KB)

    The SARTOR project has as one of its goals the development of an environment for the development of correct real-time systems. Modechart is a specification language for real-time systems developed as part of this project. Verify4 is an implementation of a verifier for certain classes of properties of systems specified using Modechart. The author describes the program Verify4 and addresses implemen... View full abstract»

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  • Experiments with a program timing tool based on source-level timing schema

    Publication Year: 1990, Page(s):72 - 81
    Cited by:  Papers (36)  |  Patents (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1016 KB)

    A timing tool has been implemented for a subset of C as an initial experiment in validating a methodology for predicting the deterministic execution times of programs. The tool is based on formal timing schema that are defined for each source level construct (procedures, statements, expressions). The tool accepts a program and bounds for each loop, and produces predictions for best and worst case ... View full abstract»

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  • From CHAOS/sup base/ to CHAOS/sup arc/: a family of real-time kernels

    Publication Year: 1990, Page(s):82 - 91
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1026 KB)

    The authors present a family of object-based real-time operating system kernels that address portability, extensibility, and customizability for low-level and subsystem-level operations. The family is extensible in that new abstractions and functionalities can be added easily and efficiently, thereby maintaining uniform kernel interfaces and permitting the implementation of domain or target machin... View full abstract»

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  • Dynamic real-time optimistic concurrency control

    Publication Year: 1990, Page(s):94 - 103
    Cited by:  Papers (50)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (892 KB)

    The authors (1990) have shown that in real-time database systems that discard late transactions, optimistic concurrency control outperforms locking. Although the optimistic algorithm used in that study, OPT-BC, did not factor in transaction deadlines in making data conflict resolution decisions, it still outperformed a deadline-cognizant locking algorithm. A discussion is presented of why adding d... View full abstract»

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  • Concurrency control in real-time databases by dynamic adjustment of serialization order

    Publication Year: 1990, Page(s):104 - 112
    Cited by:  Papers (44)  |  Patents (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (838 KB)

    A new concurrency control algorithm for real-time database systems is proposed, by which real-time scheduling and concurrency control can be integrated. The algorithm is founded on a priority-based locking mechanism to support time-critical scheduling by adjusting the serialization order dynamically in favor of high priority transactions. Furthermore, it does not assume any knowledge about the dat... View full abstract»

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  • Scheduling I/O requests with deadlines: A performance evaluation

    Publication Year: 1990, Page(s):113 - 124
    Cited by:  Papers (46)  |  Patents (10)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (1138 KB)

    The I/O scheduling problem is examined in detail. The authors present a realistic model for studying this problem in the context of a system which executes real-time transactions. The model takes advantage of the fact that reading from the disk occurs before a transaction commits, while writing to the disk usually occurs after the transaction commits. New algorithms are presented that exploit this... View full abstract»

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  • On-line routing of real-time messages

    Publication Year: 1990, Page(s):126 - 135
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (915 KB)

    Whether it is possible to have an optimal online algorithm for unidirectional ring, out-tree, in-tree, bidirectional tree, and bidirectional ring networks is discussed. The problem is considered under various restrictions of four parameters-origin node, destination node, release time and deadline. For unidirectional ring, it is shown that no such algorithm can exist unless one of the four paramete... View full abstract»

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  • Analysis of three contention protocols in distributed real-time systems

    Publication Year: 1990, Page(s):136 - 145
    Cited by:  Papers (11)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (955 KB)

    The probability of a station/node failing to deliver packets before their deadlines, called the probability of dynamic failure, P/sub dyn/, and the in -bounded delivery time, which is defined as the time period between the arrival of a packet and its delivery with probability greater than 1- in , are important performance parameters for the communication subsystems of a distributed real-time syste... View full abstract»

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  • Real-time communication in multiple token ring networks

    Publication Year: 1990, Page(s):146 - 154
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (667 KB)

    A communication architecture and a dynamic control protocol are presented for real-time communication in multiple token ring networks. The network can be formed by multiple channels through bandwidth subdivision of a high-speed ring. A flexible preemption and dynamic load allocation scheme is developed which can reduce the lost percentage of critical packets and can maintain a high channel utiliza... View full abstract»

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  • New latency bounds for atomic broadcast

    Publication Year: 1990, Page(s):156 - 165
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (698 KB)

    Tighter bounds are provided on the time required to reach agreement in a distributed system as a function of the failure model. After describing the model of a distributed system that is a context for this work the authors define several failure classes. They define a partial order on classes of failures that involves whether there is a latency penalty in converting from tolerance of one failure c... View full abstract»

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  • Agreeing on a leader in real-time (fault tolerant computer system)

    Publication Year: 1990, Page(s):166 - 172
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (670 KB)

    A method is devised for maintaining the continuing availability of a vital service in a real-time shared-memory multiprocessor fault-tolerant computer system. The essential characteristics of the service to be provided are given. The service can be correctly provided by any one operational processor acting alone. The job of selecting the processor to provide the service is the real-time leader ele... View full abstract»

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  • A robust group membership algorithm for distributed real-time systems

    Publication Year: 1990, Page(s):173 - 179
    Cited by:  Papers (18)  |  Patents (7)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (697 KB)

    An algorithm is presented by which nonfaulty processors of a group of fixed size will be able to maintain a consistent and timely knowledge of the group membership. The authors assume an architecture in which the broadcast network is accessed by some time domain multiplexing techniques where the exclusive right to transmit messages is granted to each processor once in every 'cycle'. In an executio... View full abstract»

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  • Preemptively scheduling hard-real-time sporadic tasks on one processor

    Publication Year: 1990, Page(s):182 - 190
    Cited by:  Papers (283)  |  Patents (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (680 KB)

    Consideration is given to the preemptive scheduling of hard-real-time sporadic task systems on one processor. The authors first give necessary and sufficient conditions for a sporadic task system to be feasible (i.e., schedulable). The conditions cannot, in general, be tested efficiently (unless P=NP). They do, however, lead to a feasibility test that runs in efficient pseudo-polynomial time for a... View full abstract»

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  • A stack-based resource allocation policy for realtime processes

    Publication Year: 1990, Page(s):191 - 200
    Cited by:  Papers (105)  |  Patents (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (895 KB)

    The stack resource policy (SRP) is a resource allocation policy which permits processes with different priorities to share a single runtime stack. It is a refinement of the priority ceiling protocol (PCP), which strictly bounds priority inversion and permits simple schedulability tests. With or without stack sharing, the SRP offers the following improvements over the PCP: (1) it unifies the treatm... View full abstract»

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  • Fixed priority scheduling of periodic task sets with arbitrary deadlines

    Publication Year: 1990, Page(s):201 - 209
    Cited by:  Papers (306)  |  Patents (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (731 KB)

    Consideration is given to the problem of fixed priority scheduling of period tasks with arbitrary deadlines. A general criterion for the schedulability of such a task set is given. Worst case bounds are given which generalize the C.L. Liu and J.W. Layland (1973) bound. The results are shown to provide a basis for developing predictable distributed real-time systems.<<ETX>> View full abstract»

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  • Real-time system scenarios

    Publication Year: 1990, Page(s):214 - 225
    Cited by:  Papers (20)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (836 KB)

    Two computer systems are specified which are functionally similar to subsets of existing US Navy ship and submarine systems. The computer system descriptions represent no specific system either deployed, under development, or proposed. For each system, the computer system performance requirements and computer equipment selection criterion are given. The intent is to provide meaningful test problem... View full abstract»

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  • Strategies for predictability in real-time data-flow architectures

    Publication Year: 1990, Page(s):226 - 235
    Cited by:  Papers (6)  |  Patents (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (954 KB)

    Consideration is given to the development of strategies for predictable performance in homogeneous multicomputer data-flow architectures operating in real-time. Algorithms are restricted to the class of large-grained, decision-free algorithms. The mapping of such algorithms onto the specified class of data-flow architectures is realized by a new marked graph model called ATAMM (algorithm to archit... View full abstract»

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  • Structuring large real-time systems with performance polymorphism

    Publication Year: 1990, Page(s):238 - 246
    Cited by:  Papers (8)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (915 KB)

    Sophisticated and flexible real-time systems may use several versions of a program fragment that performs a particular computation. These versions differ only in their performance parameters, such as the time required, the resources consumed, and the precision of the results. A model is presented of performance polymorphism, whereby the process of selecting a version from the available set is auto... View full abstract»

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