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Comparative study of the server-initiated lowest algorithm using a load balancing index based on the process behavior for heterogeneous environment

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CLUSTER computing-THE JOURNAL OF NETWORKS SOFTWARE TOOLS AND APPLICATIONS 2006年第3期9卷 313-319页

作者： de Mello, R. F. Trevelin, L. C. de Paiva, M. S. V. Yang, Laurence T. Univ Sao Paulo Inst Math Sci & Comp BR-13560 Sao Carlos Brazil Univ Fed Sao Carlos Dept Comp Sci BR-13560 Sao Carlos Brazil St Francis Xavier Univ Antigonish NS Canada

The availability of low cost microcomputers and the evolution of computer networks have increased the development of distributed systems. In order to get a better process allocation on distributed environments, several load balancing algorithms have been proposed. Generally, these algorithms consider as the information policy's load index the length of the CPU's process waiting queue. This paper modifies the Server-Initiated Lowest algorithm by using a load index based on the resource occupation. Using this load index the Server-Initiated Lowest algorithm is compared to the Stable symmetrically initiated, which nowadays is defined as the best choice. The comparisons are made by using simulations. The simulations showed that the modified Server-Initiated Lowest algorithm had better results than the Symmetrically Initiated one.

关键词： load balancing algorithm high performance parallel and distributed computing

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parallel Newton two-stage methods based on ILU factorizations for nonlinear systems

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NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS 2006年第7期13卷 553-572页

作者： Arnal, J. Migallon, H. Migallon, V. Penades, J. Univ Alicante Dept Ciencia Computac & Inteligencia Artificial E-03071 Alicante Spain Univ Miguel Hernandez Dept Fis & Arquitectura Comp Alicante 03202 Spain

parallel iterative algorithms based on the Newton method and on two of its variants, the Shamanskii method and the Chord method, for solving nonlinear systems are proposed. These algorithms are based on two-stage multisplitting methods where incomplete LU factorizations are considered as a mean of constructing the inner splittings. Convergence properties of these parallel methods are studied for H-matrices. Computational results of these methods on two parallel computing systems are discussed. The reported experiments show the effectiveness of these methods. Copyright (C) 2006 John Wiley & Sons, Ltd.

关键词： parallel and distributed computing nonlinear systems ILU factorizations two-stage methods Newton method

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Bounds on the client-server incremental computing

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2006年第5期E89A卷 1198-1206页

作者： Lin, Cho-chin Wang, Da-wei Hsu, Tsan-sheng Natl Ilan Univ Dept Elect Engn Yilan 260 Taiwan Acad Sinica Inst Informat Sci Taipei 115 Taiwan Natl Yang Ming Univ Taipei Taiwan

We discuss the problem of finding a dominant sequence for sending input data items from a low-end client to a server for computational intensive tasks under the realistic assumption of unpredictable communication behavior. Under this assumption, the client has to send the input data items using a specified sequence to maximize the number of computations performed by the server at any time. The sequence-finding problem is NP-hard for the general case. In this paper, we address three fundamental and useful applications: the product of two polynomials, matrices multiplication and Fast Fourier Transform. We show that the sequence-finding problems of the three applications can be solved optimally in linear time. However, we also show counter examples to rule out any possibility of finding a dominant sequence for sparse cases of the three applications. Finally, a simulation is conducted to show the usefulness of our method.

关键词： parallel and distributed computing network computing client-server Internet computing incremental computing lower and upper bounds

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A Pattern Recognition Approach for Speculative Firing Prediction in distributed Saturation State-Space Generation

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ELECTRONIC NOTES IN THEORETICAL COMPUTER SCIENCE 2006年第2期135卷 65-80页

作者： Chung, Ming-Ying Ciardo, Gianfranco Univ Calif Riverside Riverside CA 92521 USA

The saturation strategy for symbolic state-space generation is particularly effective for globallyasynchronous locally-synchronous systems. A distributed version of saturation, Saturation NOW, uses the overall memory available on a network of workstations to effectively spread the memory load, but its execution is essentially sequential. To achieve true parallelism, we explore a speculative firing prediction, where idle workstations work on predicted future event firing requests. A naive approach where all possible firings may be explored a priori, given enough idle time, can result in excessive memory requirements. Thus, we introduce a history-based approach for firing prediction that recognizes firing patterns and explores only firings conforming to these patterns. Experiments show that our heuristic improves the runtime and has a small memory overhead. The saturation strategy for symbolic state-space generation is particularly effective for globallyasynchronous locally-synchronous systems. A distributed version of saturation, SaturationNOW, uses the overall memory available on a network of workstations to effectively spread the memory load, but its execution is essentially sequential. To achieve true parallelism, we explore a speculative firing prediction, where idle workstations work on predicted future event firing requests. A naive approach where all possible firings may be explored a priori, given enough idle time, can result in excessive memory requirements. Thus, we introduce a history-based approach for firing prediction that recognizes firing patterns and explores only firings conforming to these patterns. Experiments show that our heuristic improves the runtime and has a small memory overhead.

关键词： state-space generation decision diagrams distributed systems parallel and distributed computing speculative computing pattern recognition

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Evaluating high-performance computers

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2005年第10期17卷 1239-1270页

作者： Vetter, JS de Supinski, BR Kissel, L May, J Vaidya, S Oak Ridge Natl Lab Oak Ridge TN 37992 USA Lawrence Livermore Natl Lab Livermore CA 94551 USA

Comparisons of high-performance computers based on their peak floating point performance are common but seldom useful when comparing performance on real workloads. Factors that influence sustained performance extend beyond a system's floating-point units, and real applications exercise machines in complex and diverse ways. Even when it is possible to compare systems based on their performance, other considerations affect which machine is best for a given organization. These include the cost, the facilities requirements (power, floorspace, etc.), the programming model, the existing code base, and so on. This paper describes some of the important measures for evaluating high-performance computers. We present data for many of these metrics based on our experience at Lawrence Livermore National Laboratory (LLNL), and we compare them with published information on the Earth Simulator. We argue that evaluating systems involves far more than comparing benchmarks and acquisition costs. We show that evaluating systems often involves complex choices among a variety of factors that influence the value of a supercomputer to an organization, and that the high-end computing community should view cost/performance comparisons of different architectures with skepticism. Published in 2005 by John Wiley & Sons, Ltd.

关键词： high-performance computing performance evaluation computer architecture parallel and distributed computing

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Performance evaluation of parallel iterative deepening A^* on clusters of workstations

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PERFORMANCE EVALUATION 2005年第1-4期60卷 223-236页

作者： Al-Ayyoub, AE Faculty of Computer Studies Arab Open University P.O. Box 18211 Bahrain

In this paper we investigate the performance of distributed heuristic search methods based on a well-known heuristic search algorithm, the iterative deepening A* (IDA*). The contribution of this paper includes proposing and assessing a distributed algorithm for IDA*. The assessment is based on space, time and solution quality that are quantified in terms of several performance parameters such as generated search space and real execution time among others. The experiments are conducted on a cluster computer system consisting of 16 hosts built around a general-purpose network. The objective of this research is to investigate the feasibility of cluster computing as an alternative for hosting applications requiring intensive graph search. The results reveal that cluster computing improves on the performance of IDA* at a reasonable cost. (c) 2004 Elsevier B.V. All rights reserved.

关键词： heuristic search parallel and distributed computing IDA(*) performance evaluation

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RAxML-II: a program for sequential, parallel and distributed inference of large phylogenetic

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CONCURRENCY AND COMPUTATION-PRACTICE & EXPERIENCE 2005年第14期17卷 1705-1723页

作者： Stamatakis, A Ludwig, T Meier, H Tech Univ Munich Lehrstuhl Rechnertech & Rechnerorg 110 D-85748 Garching Germany Univ Heidelberg Inst Informat D-69120 Heidelberg Germany

Inference of phylogenetic trees comprising hundreds or even thousands of organisms based on the maximum likelihood method is computationally intensive. We present simple heuristics which yield accurate trees for synthetic as well as real data and significantly reduce execution time. Those heuristics have been implemented in a sequential, parallel, and distributed program called RAxML-II which is freely available as open source code. We compare the performance of the sequential program with PHYML and MrBayes which-to the best of our knowledge-are currently the fastest and most accurate programs for phylogenetic tree inference based on statistical methods. Experiments are conducted using 50 synthetic 100 taxon alignments as well as nine real-world alignments comprising 101 up to 1000 sequences. RAxML-II outperforms MrBayes for real-world data both in terms of speed and final likelihood values. Furthermore, for real data RAxML-II requires less time (a factor of 2-8) than PHYML to reach PHYML's final likelihood values and yields better final trees due to its more exhaustive search strategy. For synthetic data MrBayes is slightly more accurate than RAxML-II and PHYML but significantly slower. The non-deterministic parallel program shows good speedup values and has been used to infer a 10 000-taxon tree comprising organisms from the domains Eukarya, Bacteria, and Archaea. Copyright (c) 2005 John Wiley & Sons, Ltd.

关键词： phylogenetic trees maximum likelihood parallel and distributed computing

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Maintaining cache coherency for B⁺ tree indexes in a shared disks cluster

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6th International Conference on High Performance computing for Computational Science (VECPAR 2005)

作者： Ohn, K Cho, H Yeungnam Univ Dept Comp Engn Kyongsan 712749 South Korea

ISBN: (纸本)3540254242

A shared disks (SD) cluster couples multiple computing nodes for high performance transaction processing, and all nodes share a common database at the disk level. To reduce the number of disk access, the node may cache both data pages and index pages in its local memory buffer. In general, index pages are accessed more often and thus cached at more nodes than their corresponding data pages. Furthermore, tree-based indexes such as B+ trees require complicated operations, e.g., root-to-leaf traversal and structure modification operation due to a page split or a page concatenation. This means that it is strongly required to devise a dedicated cache coherency scheme for index pages that takes advantage of the semantics of their access. In this paper, we propose a new cache coherency scheme for B+ tree indexes in the SD cluster. The proposed scheme can reduce the message traffic between nodes and the number of tree re-traversals. Using a simulation model of the SD cluster, we show that the proposed scheme exhibits substantial performance improvement over the previous schemes.

关键词： cluster and grid computing data processing parallel and distributed computing

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Smart Technology for Aging, Disability, and Independence: The State of the Science 1

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2005年

作者： William C. Mann PhD

ISBN: (数字)9780471743941

ISBN: (纸本)9780471696940

Independent living with smart technologies Smart Technology for Aging, Disability, and Independence: The State of the Science brings together current research and technological developments from engineering, computer science, and the rehabilitation sciences, detailing how its applications can promote continuing independence for older persons and those with disabilities. Leading experts from multiple disciplines worldwide have contributed to this volume, making it the definitive resource. The text begins with a thorough introduction that presents important concepts, defines key terms, and identifies demographic trends at work. Using detailed product descriptions, photographs and illustrations, and case studies, subsequent chapters discuss cutting-edge technologies, including: * Wearable systems * Human-computer interactions * Assisted vision and hearing * Smart wheelchairs * Handheld devices and smart phones * Visual sensors * Home automation * Assistive robotics * In-room monitoring systems * Telehealth After considering specific high-technology solutions, the text examines recent trends in other critical areas, such as basic assistive technologies, driving, transportation and community mobility, home modifications and design, and changing standards of elder care. Students and professionals in the rehabilitation sciences, health care providers, researchers in computer science and engineering, and non-expert readers will all appreciate this text's thorough coverage and clear presentation of the state of the science.

关键词： parallel and distributed computing

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An agent infrastructure for on-demand processing of remote-sensing archives

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INTERNATIONAL JOURNAL ON DIGITAL LIBRARIES 2005年第2期5卷 120-132页

作者： Yang, Yanyan Rana, Omer F. Walker, David W. Williams, Roy Georgousopoulos, Christos Caffaro, Massimo Aloisio, Giovanni Cardiff Univ Dept Comp Sci POB 916 Cardiff CF24 3XF S Glam Wales CALTECH Ctr Adv Comp Res CACR 158 79 Pasadena CA 91125 USA Univ Lecce Fac Engn Dept Innovat Engn I-73100 Lecce Italy

Advances in data collection techniques and database technologies, such as remote sensing and satellite telemetry, have led to the collection of huge amounts of data distributed among large databases and heterogeneous remote sites. Intelligent and automatic processing of the distributed data and efficiently supporting scientific collaboration between both professional and casual users is a highly demanding task. It is also particularly challenging when the system must cope with active data that is processed on-demand. These requirements have generated an urgent need for more advanced software infrastructure to create, maintain, evolve, and federate these active digital libraries of scientific data. Traditional models of distributed computing are inadequate to support such complex applications. As part of the ongoing Synthetic Aperture Radar Atlas (SARA) Digital Library project, the research presented here proposes a collaborating mobile agent approach to on-demand processing of remote sensing data. The approach, which is based on autonomous data processing and enables different image analysis algorithms to be wrapped asmobile agents, is expected to be an improvement over the static CGI-based interface and inefficient information discovery that are currently used by SARA. We discuss the agent-based infrastructure we have developed. The SARA system allows users to dispatch their compute-intensive jobs as mobile agents. Since the agents can be programmed to satisfy their specific goals, even if they move and lose contact with their creators they can survive intermittent or unreliable network connections. During their lifetime, the agents can also move themselves autonomously from one server to another for load balancing, and to enhance data locality and fault tolerance. The SARA system relies on XML to support agent communications on clusters of servers. Although the examples presented are based mainly on the SARA system, the proposed techniques are applicable to other

关键词： Digital libraries Mobile agents parallel and distributed computing XML Remote sensing

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