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Parallel and Distributed Systems, IEEE Transactions on

Issue 8 • Date Aug. 2005

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Displaying Results 1 - 12 of 12
  • [Front cover]

    Page(s): c1
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    Freely Available from IEEE
  • [Inside front cover]

    Page(s): c2
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  • On optimal replication of data object at hierarchical and transparent Web proxies

    Page(s): 673 - 685
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB) |  | HTML iconHTML  

    This paper investigates the optimal replication of data objects at hierarchical and transparent Web proxies. By transparent, we mean the proxies are capable of intercepting users' requests and forwarding the requests to a higher level proxy if the requested data are not present in their local cache. Two cases of data replication at proxies are studied: 1) proxies having unlimited storage capacities and 2) proxies having limited storage capacities. For the former case, an efficient algorithm for computing the optimal result is proposed. For the latter case, we prove the problem is NP-hard, and propose two heuristic algorithms. Extensive simulations have been conducted and the simulation results have demonstrated significant performance gain by using the proposed data replication algorithms and also shown the proposed algorithms out-perform the standard Web caching algorithm (LRU threshold method). View full abstract»

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  • Distributed resolution of network congestion and potential deadlock using reservation-based scheduling

    Page(s): 686 - 701
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1328 KB) |  | HTML iconHTML  

    Efficient and reliable communication is essential for achieving high performance in a networked computing environment. Finite network resources bring about unavoidable competition among in-flight network packets, resulting in network congestion and, possibly, deadlock. Many techniques have been proposed to improve network performance by efficiently handling network congestion and potential deadlock. However, none of them provide an efficient way of accelerating the movement of network packets in congestion toward their destinations. In this paper, we propose a new mechanism for detecting and resolving network congestion and potential deadlocks. The proposed mechanism is based on efficiently tracking paths of congestion and increasing the scheduling priority of packets along those paths. This acts to throttle other packets trying to enter those congested regions - in effect, locking out packets from congested regions until congestion has had the opportunity to disperse. Simulation results show that the proposed technique effectively disperses network congestion and is also applicable in helping to resolve potential deadlock. View full abstract»

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  • Parallel routing algorithms for nonblocking electronic and photonic switching networks

    Page(s): 702 - 713
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB) |  | HTML iconHTML  

    We study the connection capacity of a class of rearrangeable nonblocking (RNB) and strictly nonblocking (SNB) networks with/without crosstalk-free constraint, model their routing problems as weak or strong edge-colorings of bipartite graphs, and propose efficient routing algorithms for these networks using parallel processing techniques. This class of networks includes networks constructed from banyan networks by horizontal concatenation of extra stages and/or vertical stacking of multiple planes. We present a parallel algorithm that runs in O(lg2 N) time for the RNB networks of complexities ranging from O(N lg N) to O(N1.5 lg N) crosspoints and parallel algorithms that run in O(min{d* lg N, √N}) time for the SNB networks of O(N1.5 lg N) crosspoints, using a completely connected multiprocessor system of N processing elements. Our algorithms can be translated into algorithms with an O(lg N lg lg N) slowdown factor for the class of N-processor hypercubic networks, whose structures are no more complex than a single plane in the RNB and SNB networks considered. View full abstract»

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  • Perfect difference networks and related interconnection structures for parallel and distributed systems

    Page(s): 714 - 724
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB) |  | HTML iconHTML  

    In view of their applicability to parallel and distributed computer systems, interconnection networks have been studied intensively by mathematicians, computer scientists, and computer designers. In this paper, we propose an asymptotically optimal method for connecting a set of nodes into a perfect difference network (PDN) with diameter 2, so that any node is reachable from any other node in one or two hops. The PDN interconnection scheme, which is based on the mathematical notion of perfect difference sets, is optimal in the sense that it can accommodate an asymptotically maximal number of nodes with smallest possible node degree under the constraint of the network diameter being 2. We present the network architecture in its basic and bipartite forms and show how the related multidimensional PDNs can be derived. We derive the exact average internode distance and tight upper and lower bounds for the bisection width of a PDN. We conclude that PDNs and their derivatives constitute worthy additions to the repertoire of network designers and may offer additional design points that can be exploited by current and emerging technologies, including wireless and optical interconnects. Performance, algorithmic, and robustness attributes of PDNs are analyzed in a companion paper. View full abstract»

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  • Performance, algorithmic, and robustness attributes of perfect difference networks

    Page(s): 725 - 736
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB) |  | HTML iconHTML  

    Perfect difference networks (PDNs) that are based on the mathematical notion of perfect difference sets have been shown to comprise an asymptotically optimal method for connecting a number of nodes into a network with diameter 2. Justifications for, and mathematical underpinning of, PDNs appear in a companion paper. In this paper, we compare PDNs and some of their derivatives to interconnection networks with similar cost/performance, including certain generalized hypercubes and their hierarchical variants. Additionally, we discuss point-to-point and collective communication algorithms and derive a general emulation result that relates the performance of PDNs to that of complete networks as ideal benchmarks. We show that PDNs are quite robust, both with regard to node and link failures that can be tolerated and in terms of blandness (not having weak spots). In particular, we prove that the fault diameter of PDNs is no greater than 4. Finally, we study the complexity and scalability aspects of these networks, concluding that PDNs and their derivatives allow the construction of very low diameter networks close to any arbitrary desired size and that, in many respects, PDNs offer optimal performance and fault tolerance relative to their complexity or implementation cost. View full abstract»

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  • Routing permutations on baseline networks with node-disjoint paths

    Page(s): 737 - 746
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB) |  | HTML iconHTML  

    Permutation is a frequently-used communication pattern in parallel and distributed computing systems and telecommunication networks. Node-disjoint routing has important applications in guided wave optical interconnects where the optical "crosstalk" between messages passing the same switch should be avoided. In this paper, we consider routing arbitrary permutations on an optical baseline network (or reverse baseline network) with node-disjoint paths. We first prove the equivalence between the set of admissible permutations (or semipermutations) of a baseline network and that of its reverse network based on a step-by-step permutation routing. We then show that an arbitrary permutation can be realized in a baseline network (or a reverse baseline network) with node-disjoint paths in four passes, which beats the existing results [M. Vaez et al., (2000)], [G. Maier et al., (2001)] that a permutation can be realized in an n × n banyan network with node-disjoint paths in O(n12/) passes. This represents the currently best-known result for the number of passes required for routing an arbitrary permutation with node-disjoint paths in unique-path multistage networks. Unlike other unique path MINs (such as omega networks or banyan networks), only baseline networks have been found to possess such four-pass routing property. We present routing algorithms in both self-routing style and central-controlled style. Different from the recent work in [Y. Yang et al., (2003)], which also gave a four-pass node-disjoint routing algorithm for permutations, the new algorithm is efficient in transmission time for messages of any length, while the algorithm in [Y. Yang et al., (2003)] can work efficiently only for long messages. Comparisons with previous results demonstrate that routing in a baseline network proposed in this paper could be a better choice for routing permutations due to its lowest hardware cost and near-optimal transmission time. View full abstract»

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  • Performance evaluation of deterministic routings, multicasts, and topologies on RHiNET-2 cluster

    Page(s): 747 - 759
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1880 KB) |  | HTML iconHTML  

    System area networks (SANs), which usually accept arbitrary topologies, have been used to connect nodes in PC/WS clusters or high-performance storage systems. Although deadlock-free routings, multicasts, and topologies for SANs have been widely developed, their evaluation on real PC clusters was rarely done. Thus, the evaluation of routings, multicasts, and topologies in real systems is important to analyze their impact on the total systems and validate their simulation results. In this paper, we implement and evaluate deadlock-free routings and unicast-based multicasts under various topologies and channel buffer sizes on a PC cluster called RHiNET-2 with 64 hosts. Execution results show that descending layers (DL) routing and structured channel pools improve up to 57 percent of bandwidth and 34 percent of barrier synchronization time compared with up*/down* routing. They also show that, by visiting hosts in numerical order, execution time of unicast-based barrier synchronization is improved up to 28 percent compared with that in random order. However, channel buffer sizes don't affect the bandwidth in the RHiNET-2 cluster. In addition to fundamental evaluation, we appraise them using NAS Parallel Benchmarks, and the DL routing achieves 3.2 percent improvement on their execution time compared with up*/down* routing. View full abstract»

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  • An analysis of EDF schedulability on a multiprocessor

    Page(s): 760 - 768
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    A new schedulability test is derived for preemptive deadline scheduling of periodic or sporadic real-time tasks on a single-queue m-server system. The new test allows the task deadline to be more or less than the task period, and is based on a new analysis concept, called a μ-busy interval. This generalizes a result of Goossens et al. [2003] that a system of periodic tasks with maximum individual task utilization umax is EDF-schedulable on m processors if the total utilization does not exceed m(1 max)+umax. The new test allows the analysis of hybrid EDF-US [x] scheduling, and the conclusion that EDF-US[1/2] is optimal, with a guaranteed worst-case schedulable utilization of (m +1)/2. View full abstract»

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  • TPDS Information for authors

    Page(s): c3
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  • [Back cover]

    Page(s): c4
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Aims & Scope

IEEE Transactions on Parallel and Distributed Systems (TPDS) is published monthly. It publishes a range of papers, comments on previously published papers, and survey articles that deal with the parallel and distributed systems research areas of current importance to our readers.

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Meet Our Editors

Editor-in-Chief
David Bader
College of Computing
Georgia Institute of Technology