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[1991] Proceedings Twelfth Real-Time Systems Symposium

4-6 Dec. 1991

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Displaying Results 1 - 25 of 30
  • Proceedings. Twelfth Real-Time Systems Symposium (Cat. No.91CH3090-8)

    Publication Year: 1991
    Request permission for commercial reuse | PDF file iconPDF (71 KB)
    Freely Available from IEEE
  • Load adjustment in adaptive real-time systems

    Publication Year: 1991, Page(s):160 - 170
    Cited by:  Papers (89)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (840 KB)

    A framework is given for discussing how to adjust load in order to handle periodic processes whose timing parameters vary with time. The schedulability of adjustable periodic processes by a preemptive fixed priority scheduler is formulated in terms of a configuration selection problem. Specifically, two process transformations are introduced for the purpose of deriving a bound for the achievable u... View full abstract»

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  • Optimization in real time

    Publication Year: 1991, Page(s):150 - 159
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (732 KB)

    A search algorithm called real-time search (RTS) for solving combinatorial optimization problems under real-time constraints is presented. The algorithm aims at finding the best possible solution within a given deadline. Since this objective is generally not achievable without first solving the problem, the authors use an alternative heuristic objective that looks for the solution with the best as... View full abstract»

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  • A priority ceiling protocol for multiple-instance resources

    Publication Year: 1991, Page(s):140 - 149
    Cited by:  Papers (7)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (680 KB)

    A systematic optimization process for multiple-instance resource sharing in real-time systems is presented. The authors derive the schedulability condition for systems with such resources and present an algorithm which can be used to divide a resource pool into smaller groups in order to improve the worst-case blocking behavior. They present the system model used and review some related work. The ... View full abstract»

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  • On non-preemptive scheduling of period and sporadic tasks

    Publication Year: 1991, Page(s):129 - 139
    Cited by:  Papers (163)  |  Patents (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    A fundamental problem in the theory of real-time scheduling is examined: scheduling a set of periodic or sporadic tasks on a uniprocessor without preemption and without inserted idle time. The authors give a necessary and sufficient set of conditions C for a set of periodic or sporadic tasks to be schedulable for arbitrary release times of the tasks. They show that any set of periodic or ... View full abstract»

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  • Run-time monitoring of real-time systems

    Publication Year: 1991, Page(s):74 - 83
    Cited by:  Papers (43)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (748 KB)

    A model and an implementation of a run-time environment for specifying and monitoring properties of real-time systems are presented. The proposed approach supports annotating real-time programs with events that are recorded and examined at run-time. The authors provide two general methods for synchronous or asynchronous monitoring of real-time constraints. In the synchronous case, a system constra... View full abstract»

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  • Fixed priority scheduling periodic tasks with varying execution priority

    Publication Year: 1991, Page(s):116 - 128
    Cited by:  Papers (49)  |  Patents (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1064 KB)

    The problem of fixed priority scheduling of periodic tasks where each task's execution priority may vary is considered. Periodic tasks are decomposed into serially executed subtasks, where each subtask is characterized by an execution time and a fixed priority and is permitted to have a deadline. A method for determining the schedulability of each task is presented along with its theoretical under... View full abstract»

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  • A partial evaluator for the Maruti hard real-time system

    Publication Year: 1991, Page(s):64 - 73
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (708 KB)

    The use of high-level programming constructs makes it difficult to estimate at compile-time the execution time and resource requirements of a program. The authors contend that partial evaluation provides a solution to this problem. They describe the application of partial evaluation to programming languages for hard-real-time systems and give examples of programs handled by the techniques. They di... View full abstract»

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  • On using priority inheritance in real-time databases

    Publication Year: 1991, Page(s):210 - 221
    Cited by:  Papers (22)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (944 KB)

    The authors investigate solutions to the priority inversion problem in a real-time database where two-phase locking is employed for concurrency control. They examine two basic schemes for addressing the priority inversion problem, one based on priority inheritance and the other based on priority abort. The authors also study a new scheme, called conditional priority inheritance, which attempts to ... View full abstract»

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  • On the competitiveness of on-line real-time task scheduling

    Publication Year: 1991, Page(s):106 - 115
    Cited by:  Papers (19)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (756 KB)

    The authors study the performance of online algorithms in environments where no value is obtained for the partial execution of a request. They prove that no online scheduling algorithm can have a competitive factor greater than 0.25 times the optimal. They further refine this bound by considering the effect of the loading factor. Other models of task systems (for example, tasks systems consisting ... View full abstract»

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  • Program representation and translation for predictable real-time systems

    Publication Year: 1991, Page(s):53 - 63
    Cited by:  Papers (29)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (960 KB)

    A basic approach to the problem of program translation for systems using explicit plan scheduling is described. One of the goals is to establish a source language, Spring-C, that can serve as a target for many languages. The author discusses a method for deriving behavioral predictions while translating between the programming and run-time representations used by the Spring system. A graph represe... View full abstract»

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  • Hartstone distributed benchmark: requirements and definitions

    Publication Year: 1991, Page(s):199 - 208
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (724 KB)

    A series of benchmark requirements, the Hartstone distributed benchmark (HDB), to be used in testing the ability of real-time distributed systems (RTDSs), to handle real-time applications, is defined. The HDB experiments deliver figures of merit for the end-to-end scheduling of messages, which integrates the processor scheduling domain and the communication scheduling domain. In the HDB experiment... View full abstract»

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  • Load sharing with consideration of future task arrivals in heterogeneous distributed real-time systems

    Publication Year: 1991, Page(s):94 - 103
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    The authors propose a new loading sharing (LS) algorithm for real-time applications that accounts for the effect of future task arrivals on locating the best receiver for each unguaranteed task. The LS algorithm minimizes not only the probability of transferring an unguaranteed task T to an incapable node with Bayesian analysis, but also the probability that a remote node fails to guarant... View full abstract»

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  • Earliest deadline scheduling for real-time database systems

    Publication Year: 1991, Page(s):232 - 242
    Cited by:  Papers (73)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (872 KB)

    A new priority assignment algorithm called adaptive earliest deadline (AED) is given that stabilizes the overload performance of the earliest deadline policy in a real-time database system (RTDBS) environment. The AED algorithm uses a feedback control mechanism to achieve this objective and does not require knowledge of transaction characteristics. Using a detailed simulation model, the authors co... View full abstract»

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  • RTC: language support for real-time concurrency

    Publication Year: 1991, Page(s):43 - 52
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (816 KB)

    Language constructs for the expression of timing and concurrency requirements in distributed real-time programs are presented. The approach to concurrent real-time programming is to explicitly express real-time concurrency constraints in a program and allow the run-time system to enforce them. To define these constraints precisely, the authors develop a real-time concurrency model that combines an... View full abstract»

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  • Early experience with POSIX 1003.4 and POSIX 1003.4 A

    Publication Year: 1991, Page(s):190 - 198
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (788 KB)

    Two proposed IEEE standards for real-time operating systems support, POSIX.4 and POSIX.4a, are proceeding towards IEEE approval and will eventually become international standards. The authors provide a brief overview of the facilities of POSIX.4 and POSIX.4a. They concentrate on a few of the critical features that POSIX.4 and POSIX.4a provide and describe the POSIX.4 scheduling interface. The POSI... View full abstract»

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  • A requirements specification method for adaptive real-time systems

    Publication Year: 1991, Page(s):264 - 273
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (688 KB)

    A method for facilitating the specification and analysis of semihard real-time systems is described. The authors introduce the notion of an activity, the fundamental unit of computation upon which the methodology is based. They present a notation for creating an integrated requirements model which addresses the functional, behavioral, temporal, and information aspects of a semihard real-time syste... View full abstract»

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  • Efficient synchronization of clocks in a distributed system

    Publication Year: 1991, Page(s):22 - 31
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (820 KB)

    A probabilistic clock synchronization algorithm is proposed where processors in the system exchange time stamps and synchronize to a common clock value. Most of the previous algorithms for this problem have been based on a master-slave approach where all the slave processors synchronize to the clock value of a master. These algorithms are not distributed in nature and some of the assumptions made ... View full abstract»

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  • Real-time features for Ada 9X

    Publication Year: 1991, Page(s):172 - 180
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (856 KB)

    Ada 9X is a revision of the Ada programming language standard. This revision includes some changes that are intended to improve Ada's usefulness for real-time applications. The changes under consideration include multiple clocks, new forms of delay statements, a new low-level data synchronization scheme based on a limited form of priority inheritance, and a mechanism for asynchronously controlling... View full abstract»

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  • An object oriented model for parallel and reactive systems

    Publication Year: 1991, Page(s):84 - 93
    Cited by:  Papers (30)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (692 KB)

    MO2 is an object-oriented model which integrates features of database management systems (DBMSs) and features of real-time systems. It allows for the definition of different kinds of relationships between objects: generalization/specialization, aggregation, and association. Its principal feature is the ability to distinguish passive objects and active objects. The passive objects react only throug... View full abstract»

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  • Enhancing real-time DBMS performance with multiversion data and priority based disk scheduling

    Publication Year: 1991, Page(s):222 - 231
    Cited by:  Papers (14)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (788 KB)

    Real-time multiversion concurrency control algorithms are proposed, to: increase concurrency, adjust the serialization order dynamically and work without an estimate of a transaction's runtime. The authors also propose disk scheduling algorithms which consider not only the transactions which request input/output (I/O) but also those affected by I/O. They consider transactions which are directly af... View full abstract»

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  • Specification and verification of real-time embedded systems using time-constrained reactive automata

    Publication Year: 1991, Page(s):244 - 253
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (848 KB)

    The authors briefly review the time-constrained reactive automata (TRA) model and its use in the specification and verification of real-time embedded systems. Among its salient features is a fundamental notion of space and time that restricts the expensiveness of the model in a way that allows the specification of only reactive, spontaneous, and causal computation. Using the TRA formalism, there i... View full abstract»

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  • Using objects and actions to provide fault tolerance in distributed, real-time applications

    Publication Year: 1991, Page(s):276 - 285
    Cited by:  Papers (7)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (668 KB)

    An object-oriented model is developed for structuring distributed real-time applications. Atomic atoms (atomic transactions) and exception handling techniques are used to introduce fault tolerance. Additional techniques are then developed to permit application and device specific commit and abort processing. Objects can be replicated to increase their availability. The authors examine the reasons ... View full abstract»

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  • Towards an automatic synthesis system for real-time software

    Publication Year: 1991, Page(s):34 - 42
    Cited by:  Papers (10)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (768 KB)

    An automatic synthesis system for real-time software is described. It is argued that the presence of strict operation requirements, such as task-level timing constraints and compiler and target platform constraints, guides synthesis. An automatic software synthesis system, RT-SYN, integrates platform characteristics to synthesize real-time software which meets hard deadline design requirements. Th... View full abstract»

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  • Building a predictable avionics platform in Ada: a case study

    Publication Year: 1991, Page(s):181 - 189
    Cited by:  Papers (62)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (776 KB)

    In an effort to promote the use of Ada in embedded system development, a realistic avionics application model whose hard real-time properties are fully predictable has been generated. This was done starting with a rate monotonic analysis of a set of typical fully synchronized periodic and aperiodic avionics tasks drawn from an idealized attack aircraft mission computer. The authors describe this a... View full abstract»

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