L.R. Welch, B. Ravindran, B. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time Systems," Proc. IEEE Real-Time Systems Symp., pp. 72-81, Dec. 1998.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....violation. Therefore, even though a good static mapping of real time applications may ensure that no QoS constraints are violated when the system is first put in operation, dynamic mapping approaches may be needed to re allocate resources at run time to avoid QoS violations, e.g. 20] 8] 21] [22], 9] 23] This work uses a generalized performance metric that is suitable for evaluating a statically derived mapping for systems that operate in changing environments [24] The changes in environment are reflected in the variations of run time parameters. The general goal of this research is ....

....completed before a certain time constraint. Therefore using a run time parameter to prolong the need for the dynamic scheduler in the target system is one of the contributions of this research. The system model assumed in our research is similar to that of the DeSiDeRaTa project (e.g. 20] 8] [22], 9] 47] 23] in that both use continuously running applications and a heterogeneous distributed system. The di#erence is that, while our work focuses on deriving a static mapping of the applications to resources, the DeSiDeRaTa project focuses on dynamically re mapping the resources to meet ....

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L. R. Welch, B. Ravindran, B. A. Shirazi, and C. Bruggeman, "Specification and modeling of dynamic, distributed real-time systems," in 19th IEEE Real-Time Systems Symposium (RTSS '98), pp. 72--81, Dec. 1998.

....We first justify the suitability of path based paradigm and feedback control based paradigm for resource management in AHSCS, then we motivate the need for developing a new resource management methodology combining them. B. 1 Motivation for Path Based Paradigm The dynamic path paradigm [8] [9] is convenient for specifying end to end system objectives and for analyzing timeliness, dependability, and scalability of distributed real time systems. The notion of a dynamic path is also useful to describe systems with dynamic variability, wherein the behavioral characteristics of the various ....

....In this section, we first provide an overview on dynamic paths, then identify the schedulable entities (i.e. the paths) and their characteristics, and finally propose a novel resource management methodology with solution for the AHSCS. A. Background on Dynamic Paths As defined in [8] [9], a dynamic path consists of a data event source, a data event stream and a data event consumer. The data event source produces data events, which cause the data event consumer to perform processing. Based on the nature of the source and consumer, dynamic paths can be classified into the following ....

L.R. Welch, B. Ravindran, B.A. Shirazi, and C. Bruggeman, "Specification and modeling of dynamic, distributed real-time systems," Real-Time Systems Symposium, pp.72-81, 1998.

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L.R. Welch, B. Ravindran, B. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time Systems," Proc. IEEE Real-Time Systems Symp., pp. 72-81, Dec. 1998.

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L. R. Welch, B. Ravindran, B. Shirazi, and C. Bruggeman, "Specification and modeling of dynamic, distributed real-time systems," in Proceedings of The IEEE Real-Time Systems Symposium, December 1998, pp. 72--81.

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L. R. Welch, B. Ravindran, B. A. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time 53 Systems," Proceedings of the 19th IEEE Real-Time Systems Symposium, pp. 72 - 81, December 1998.

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L. Welch, B. Ravindran, B. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time Systems," Proceedings of the Nineteenth IEEE Real-Time Systems Symposium, pages 72-81, December 1998.

.... that allows real time systems (systems that must perform in a timely manner) to meet their performance constraints in dynamic environments (such as defense [6] and space [5] by (1) monitoring realtime performance and (2) reallocating resources as needed to provide adequate real time performance [1, 2, 3]. This paper presents patterns (i.e. solutions to commonly occurring design problems [4] that have emerged in resource management software. The specific patterns discussed are as follows: Resource instrumentation: monitoring the status (e.g. availability and utilization) of hardware ....

....and their dependencies. Specification File Management parses hardware configuration and software specification files; the specification files describe the characteristics of the computing and network resources and the features and real time requirements of the information system software [1, 2]. The other subsystems use the information from the specification files. The Resource Instrumentation and Control subsystem has two main purposes. First, its Resource Monitor component is used to gather information about the utilization and availability of the computing and network resources [2, ....

L. R. Welch, B. Ravindran, B. A. Shirazi and C.Bruggeman, "Specification and modeling of dynamic, distributed real-time systems," in Proceedings of The 19 th IEEE Real-Time Systems Symposium, 72-81, IEEE Computer Society Press, 1998.

....timeliness QoS management algorithms. Furthermore, we focus on replication as the recovery action. Details of experiments that validate the effectiveness of real time and survivability services (by replication and migration) and measure the middleware intrusiveness can be found in [RWS99, WRSB98]. Section 10.1 summarizes the experimental environment. We describe the application workload and the metrics of interest in Section 10.2. Section 10.3 presents the results the experiment and their analysis. 10.1 The Experimental Environment Our experimental environment consists of the real time ....

L. R. Welch, B. Ravindran, B. A. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time Systems," Proceedings of The 19th IEEE Real-Time Systems Symposium, pages 72 - 81, December 1998.

....as part of [Quo97] has produced the DeSiDeRaTa middleware [Rav00] The middleware allows the specification and negotiation of real time and survivability requirements of asynchronous real time distributed systems such as the U. S. Naval Surface Warfare Center s (NSWC) Anti Air Warfare system [WRSB98]. DeSiDeRaTa was demonstrated [Quo98] and transitioned to NSWC s HiPer D SC 21 test bed [HiPerD] 2 The classical real time communication literature focuses primarily on static systems, where the communication parameters of the application such as message latencies, message periods, and message ....

....with the processing of all the data items (generated by the sensor in that cycle) Thus, the deadline requirement of the periodic tasks must be 3 This application model that we are presenting here is based on the Anti Air Warfare (AAW) real time, command and control system of the U.S. Navy [WRSB98]. Operating Environment Assessment Task Initiation Task Guidance Task Sensor Sensor Actuator Actuator data event event data data stream data stream action control of action Real Time System Application (periodic) aperiodic) transient periodic) 6 adhered in all cycles, ....

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L. R. Welch, B. Ravindran, B. A. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time Systems," Proceedings of The 19th IEEE Real-Time Systems Symposium, pages 72 - 81, December 1998.

....(per period) may result in any number of aperiodic events that trigger the execution of the initiation and guidance tasks, which the tasks must respond and complete within the deadline. After a careful study of the Anti Air Warfare (AAW) real time command and control (C2) system of the U.S. Navy [21], we have observed that the resource needs of the tasks are significantly influenced by the size of the data and the event streams. Size of the data stream refers to the number of data items (sensor reports) that the assessment and guidance tasks have to process during a single execution cycle, ....

L. R. Welch, B. Ravindran, B. A. Shirazi, and C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-Time Systems," Proceedings of The 19th IEEE Real-Time Systems Symposium, pages 72 - 81, December 1998.

....determined based on characteristics of the threat. For example, a fast moving, nearby threat will require issuing more frequent guidance commands than a slower moving threat that is farther away. QoS Specification The DeSiDeRaTa environment includes a specification language called D Spec [Welch98a] that is used for specification of QoS requirements of distributed systems, such as DynBench, that operate in unknown environments. D Spec is useful for describing real time QoS requirements in terms of end to end paths through application programs. Experiment Generator: In addition to the ....

L.R. Welch, B. Ravindran, B. Shirazi, C. Bruggeman, "Specification and Modeling of Dynamic, Distributed Real-time Systems," Proceedings of the 19 th IEEE Real-Time Systems Symposium (RTSS'98), Dec. 1998, pp. 72-81.

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