distributed real-time systems play an increasingly vital role in our society. The most important aspect of such systems is the scheduling algorithm, which must guarantee that every job in the system will meet its dead...
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distributed real-time systems play an increasingly vital role in our society. The most important aspect of such systems is the scheduling algorithm, which must guarantee that every job in the system will meet its deadline, providing high-quality (precise) results. In this paper we evaluate by simulation the performance of strategies for the scheduling of parallel jobs (gangs) in a homogeneous distributed real-time system with possible software faults. For each scheduling policy we provide an alternative version which allows imprecise computations. We propose a performance metric applicable to our problem, which takes into account the number of jobs guaranteed, as well as the precision of the results of each guaranteed job. The simulation results show that the alternative versions of the algorithms outperform their respective counterparts. To the best of our knowledge, a real-time gang scheduling approach that utilizes imprecise computations has never been discussed in the literature before.
Tools are becoming increasingly important to efficiently utilize the computing power available in contemporary large scale systems. The drastic increase in the size and the complexity of systems require tools to be sc...
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ISBN:
(纸本)9781424437504
Tools are becoming increasingly important to efficiently utilize the computing power available in contemporary large scale systems. The drastic increase in the size and the complexity of systems require tools to be scalable while producing meaning full and easily digestible information that may help the user pin-point problems at scale. The goal of this tutorial is to introduce some state-of-the-art performance tools from three different organizations to a diverse audience group. Together these tools provide a broad spectrum of capabilities necessary to analyze the performance of scientific and engineering applications on a variety of large and small scale systems.
Dynamic loop scheduling (DLS) algorithms provide application-level load balancing of loop iterates, with the goal of maximizing application performance on the underlying system. These methods use run-time information ...
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ISBN:
(纸本)9780769536804
Dynamic loop scheduling (DLS) algorithms provide application-level load balancing of loop iterates, with the goal of maximizing application performance on the underlying system. These methods use run-time information regarding the performance of the application's execution (for which irregularities change over time). Many DLS methods are based on probabilistic analyses, and therefore account for unpredictable variations of application and system related parameters. Scheduling scientific and engineering applications in large-scale distributedsystems (possibly shared with other users) makes the problem of DLS even more challenging. Moreover, the chances of failure, such as processor or link failure, are high in such large-scale systems. In this paper, we employ the hierarchical approach for three DLS methods, and propose metrics for quantifying their robustness with respect to variations of two parameters (load and processor failures), for scheduling irregular applications in large-scale heterogeneous distributedsystems.
Enterprise architectures (EA) embody the business objectives, processes and information technology infrastructure reflecting the desired incorporation and standardization requirements of a company's operating mode...
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ISBN:
(纸本)9780769536422
Enterprise architectures (EA) embody the business objectives, processes and information technology infrastructure reflecting the desired incorporation and standardization requirements of a company's operating model. It is vital that during the initial design stages the software system's architecture aligns with the EA. While frameworks exist to check the alignment of enterprise and system architectures, there is an assumption of well-defined requirements derived from the EA's business objectives. This transition is non-trivial as the EA can be a significant document representing the viewpoints of the stakeholders. This paper proposes and illustrates, using the Grounded Theory Methodology, a systematic, qualitative procedure, to extract the functional and non-functional enterprise requirements from the EA and/or system description. The contribution of this work is to further systematize the alignment and traceability of EA and system architectures and provide the initial requirements and system models necessary for supporting the of enterprise systems.
Multicore processors with each core supporting multiple threads are becoming commonplace. To take advantage of these hardware advances, application software has to evolve and embrace parallel processing, otherwise the...
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ISBN:
(纸本)9781605586557
Multicore processors with each core supporting multiple threads are becoming commonplace. To take advantage of these hardware advances, application software has to evolve and embrace parallel processing, otherwise the performance growth that we have come to expect with each generation of processor technology will not be met. But, introducing parallelism into software is difficult and error prone. Robust debugging tools are required to help developers build efficient, scalable, multi-threaded applications. In this paper we present a data race detection tool and a set of techniques that were used to improve the efficiency of the tool. Also, we present detailed performance overheads for the tool using a number of industrial strength applications. Copyright 2009 ACM.
The need to exploit multi-core systems for parallel processing has revived the concept of dataflow. In particular the Dataflow Multithreading architectures have proven to be good candidates for these systems. In this ...
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ISBN:
(纸本)9780769536804
The need to exploit multi-core systems for parallel processing has revived the concept of dataflow. In particular the Dataflow Multithreading architectures have proven to be good candidates for these systems. In this work we propose an abstraction layer that enables compiling and running a program written for an abstract Dataflow Multithreading architecture on different implementations. More specifically, we present a set of compiler directives that provide the programmer with the means to express most types of dependencies between code segments. In addition, we present the corresponding toolchain that transforms this code into a form that can be compiled for different implementations of the model. As a case study for this work, we present the usage of the toolchain for the TFlux and DTA architectures.
The objective of this research is to develop a mobile agent platform for embedded systems. This platform is integrated into the features of a real-time kernel allowing mobile agent-based software to be implemented wit...
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ISBN:
(纸本)9780889867840
The objective of this research is to develop a mobile agent platform for embedded systems. This platform is integrated into the features of a real-time kernel allowing mobile agent-based software to be implemented within a cluster of homogeneous embedded systems. The applications targeted by this platform pertain to the field of pervasive computing and more particularly, as applied to the "smart space" paradigm.
This paper describes an approach for conformance testing of mobile and distributedsystems. The approach is based on kiltera - a novel, high-level language supporting the description and execution of models of concurr...
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ISBN:
(纸本)9781605586557
This paper describes an approach for conformance testing of mobile and distributedsystems. The approach is based on kiltera - a novel, high-level language supporting the description and execution of models of concurrent, mobile, distributed, and timed computation. In our approach, a kiltera model of the system is constructed from a high-level model which describes system behavior using, e.g., a suitable UML profile. Check points are identified in the implementation under test (IUT) and the kiltera model and both are instrumented appropriately at these check points. During execution, relevant information flows from the IUT to the kiltera model which signals any non-conformance detected. Unique features of our approach include the support for mobility, distribution, time, dynamic creation and deletion of agents, and distributed monitoring. We describe the approach and a prototype implementation using a running example for illustration. Results of first, preliminary experiments are reported. Copyright 2009 ACM.
This paper presents an improved control strategy for parallel inverters so as to better manage power sharing among the distributed generation units in a microgrid. The proposed control strategy combines both power and...
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ISBN:
(纸本)9789604741199
This paper presents an improved control strategy for parallel inverters so as to better manage power sharing among the distributed generation units in a microgrid. The proposed control strategy combines both power and voltage control schemes implemented on the voltage source inverters which are used as power electronics interface systems for conversion of power generated by fuel cell and photovoltaic generation units. Dynamic models of the fuel cell and photovoltaic systems available in the PSCAD/EMTDC simulation software are used as distributed generation units present in the microgrid. To evaluate the effectiveness of the developed control strategy, the microgrid is operated in grid connected, islanding and transition modes of operation.
The actor programming model offers a promising model for developing reliable parallel and distributed code. Actors provide. exibility and scalability: local execution may be interleaved, and distributed nodes may oper...
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ISBN:
(纸本)9780769538914
The actor programming model offers a promising model for developing reliable parallel and distributed code. Actors provide. exibility and scalability: local execution may be interleaved, and distributed nodes may operate asynchronously. The resulting nondeterminism is captured by nondeterministic processing of messages. To automate testing, researchers have developed several tools tailored to specific actor systems. As actor languages and libraries continue to evolve, such tools have to be reimplemented. Because many actor systems are compiled to Java bytecode, we have developed Basset, a general framework for testing actor systems compiled to Java bytecode. We illustrate Basset by instantiating it for the Scala programming language and for the ActorFoundry library for Java. Our implementation builds on Java PathFinder, a widely used model checker for Java. Experiments show that Basset can effectively explore executions of actor programs;e. g., it discovered a previously unknown bug in a Scala application.
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