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Parallel and Distributed Systems, IEEE Transactions on

Issue 12 • Date Dec. 2008

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Displaying Results 1 - 9 of 9
  • Efficient Directional Network Backbone Construction in Mobile Ad Hoc Networks

    Publication Year: 2008 , Page(s): 1601 - 1613
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2577 KB) |  | HTML iconHTML  

    In this paper, we consider the issue of constructing an energy-efficient virtual network backbone in mobile ad hoc networks (MANETs) for broadcasting applications using directional antennas. In directional antenna models, the transmission/reception range is divided into several sectors and one or more sectors can be switched on for transmission. Therefore, data forwarding can be restricted to certain directions (sectors), and both energy consumption and interference can be reduced. We develop the notation of directional network backbone using the directional antenna model, and form the problem of the directional connected dominating set (DCDS) which is an extreme case of the directional network backbone using an unlimited number of directional antennas. The minimum DCDS problem is proved to be NP-complete. A localized heuristic algorithm for constructing a small DCDS and two extensions of the algorithm are proposed. Performance analysis includes an analytical study in terms of an approximation ratio and a simulation study on the proposed algorithms using both a custom simulator and ns2. View full abstract»

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  • Replica Placement and Access Policies in Tree Networks

    Publication Year: 2008 , Page(s): 1614 - 1627
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1376 KB) |  | HTML iconHTML  

    In this paper, we discuss and compare several policies to place replicas in tree networks, subject to server capacity and Quality of Service (QoS) constraints. The client requests are known beforehand, while the number and location of the servers are to be determined. The standard approach in the literature is to enforce that all requests of a client be served by the closest server in the tree. We introduce and study two new policies. In the first policy, all requests from a given client are still processed by the same server, but this server can be located anywhere in the path from the client to the root. In the second policy, the requests of a given client can be processed by multiple servers. One major contribution of this paper is to assess the impact of these new policies on the total replication cost. Another important goal is to assess the impact of server heterogeneity. In this paper, we establish several new complexity results, and provide several efficient polynomial heuristics for NP-complete instances of the problem. The absolute performance of these heuristics is assessed by comparison with the optimal solution provided by the formulation of the problem in terms of the solution of an integer linear program. View full abstract»

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  • Algorithm-Based Fault Tolerance for Fail-Stop Failures

    Publication Year: 2008 , Page(s): 1628 - 1641
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2343 KB) |  | HTML iconHTML  

    Fail-stop failures in distributed environments are often tolerated by checkpointing or message logging. In this paper, we show that fail-stop process failures in ScaLAPACK matrix-matrix multiplication kennel can be tolerated without checkpointing or message logging. It has been proved in previous algorithm-based fault tolerance that, for matrix-matrix multiplication, the checksum relationship in the input checksum matrices is preserved at the end of the computation no mater which algorithm is chosen. From this checksum relationship in the final computation results, processor miscalculations can be detected, located, and corrected at the end of the computation. However, whether this checksum relationship can be maintained in the middle of the computation or not remains open. In this paper, we first demonstrate that, for many matrix matrix multiplication algorithms, the checksum relationship in the input checksum matrices is not maintained in the middle of the computation. We then prove that, however, for the outer product version algorithm, the checksum relationship in the input checksum matrices can be maintained in the middle of the computation. Based on this checksum relationship maintained in the middle of the computation, we demonstrate that fail-stop process failures (which are often tolerated by checkpointing or message logging) in ScaLAPACK matrix-matrix multiplication can be tolerated without checkpointing or message logging. View full abstract»

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  • Design and Potential Performance of Goal-Oriented Job Scheduling Policies for Parallel Computer Workloads

    Publication Year: 2008 , Page(s): 1642 - 1656
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3452 KB) |  | HTML iconHTML  

    To balance multiple scheduling performance requirements on parallel computer systems, traditional job schedulers use many parameters that can be configured to define job or queue priorities. Offering many parameters seems flexible, but in reality tuning the values for the parameters is highly challenging. To simplify the task of resource management, we propose goal-oriented policies, which allow system administrators to specify high-level performance objectives, rather than tuning low-level scheduling parameters. We study the design of goal-oriented policies, including (1) appropriate multi-objective models for specifying trade-offs between objectives, (2) efficient search algorithms for searching the best schedule at each scheduling decision point, and (3) appropriate performance measures to be optimized in the objectives with respect to two common performance requirements: preventing starvation and favoring shorter jobs. We compare goal-oriented policies with widely used backfill policies. Policies are evaluated by simulation using ten monthly workloads that ran on a Linux cluster (IA-64) from NCSA. Our results show that by automatically optimizing performance according to the given objectives through search, goal-oriented policies can simultaneously outperform FCFS-backfill and LXF-backfill, which are designed in favor of the maximum wait and average slowdown, respectively. View full abstract»

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  • A Novel O(1) Deadlock Detection Methodology for Multiunit Resource Systems and Its Hardware Implementation for System-on-Chip

    Publication Year: 2008 , Page(s): 1657 - 1670
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3016 KB) |  | HTML iconHTML  

    This article describes a novel parallel multi-unit resource deadlock detection algorithm (MDDA) and its hardware implementation (MDDU). The contributions are (i) the first O(1) hardware deadlock detection, (ii) reduced O(min(m, n)) preparation, where m and n are the number of processes and resources, respectively, and (iii) support for multi-unit resources. O(min(m, n)), previously O(mtimesn), is achieved by performing all the searches for sink nodes for each and every resource in parallel in hardware over two matrices representing resource allocations as well as other auxiliary matrices. MDDU provides a fast and deterministic deadlock detection mechanism for multiprocessor system-on-chips (MPSoCs), which we predict will become prevalent in the near future in system designs. Our experiments demonstrate that MDDU always takes two clock cycles to detect deadlock regardless the size of the system. Lastly, the MPSoC area overhead due to MDDU is small, approximately 0.024 percent for MDDU16 x 16 on our example MPSoC. View full abstract»

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  • Linear Programming-Based Affinity Scheduling of Independent Tasks on Heterogeneous Computing Systems

    Publication Year: 2008 , Page(s): 1671 - 1682
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (823 KB) |  | HTML iconHTML  

    Resource management systems (RMS) are an important component in heterogeneous computing (HC) systems. One of the jobs of an RMS is the mapping of arriving tasks onto the machines of the HC system. Many different mapping heuristics have been proposed in recent years. However, most of these heuristics suffer from several limitations. One of these limitations is the performance degradation that results from using outdated global information about the status of all machines in the HC system. This paper proposes several heuristics which address this limitation by only requiring partial information in making the mapping decisions. These heuristics utilize the solution to a linear programming (LP) problem which maximizes the system capacity. Simulation results show that our heuristics perform very competitively while requiring dramatically less information. View full abstract»

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  • Analysis of TTL-Based Consistency in Unstructured Peer-to-Peer Networks

    Publication Year: 2008 , Page(s): 1683 - 1694
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1827 KB) |  | HTML iconHTML  

    Consistency maintenance is important to the sharing of dynamic contents in peer-to-peer (P2P) networks. The TTL-based mechanism is a natural choice for maintaining freshness in P2P content sharing. This paper investigates TTL-based consistency maintenance in unstructured P2P networks. In this approach, each replica is assigned an expiration time beyond which the replica stops serving new requests unless it is validated. While TTL-based consistency is widely explored in many client-server applications, there has been no study on TTL-based consistency in P2P networks. Our main contribution is an analytical model that studies the search performance and the freshness of P2P content sharing under TTL-based consistency. Due to the random nature of request routing, P2P networks are fundamentally different from most existing TTL-based systems in that every node with a valid replica has the potential to serve any other node. We identify and discuss the factors that affect the performance of P2P content sharing under TTL-based consistency. Our results indicate a tradeoff between search performance and freshness: the search cost decreases sublinearly with decreasing freshness of P2P content sharing. We also compare two types of unstructured P2P networks and find that clustered P2P networks improve the freshness of content sharing over flat P2P networks under TTL-based consistency. View full abstract»

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  • Efficient and Scalable Consistency Maintenance for Heterogeneous Peer-to-Peer Systems

    Publication Year: 2008 , Page(s): 1695 - 1708
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3454 KB) |  | HTML iconHTML  

    Consistency maintenance mechanism is necessary for the emerging peer-to-peer applications due to their frequent data updates. Centralized approaches suffer single point of failure, while previous decentralized approaches incur too many duplicate update messages because of locality-ignorant structures. To address this issue, we propose a scalable and efficient consistency maintenance scheme for heterogeneous P2P systems. Our scheme takes the heterogeneity nature into account and forms the replica nodes of a key into a locality-aware hierarchical structure, in which the upper layer is DHT-based and consists of powerful and stable replica nodes, while a replica node at the lower layer attaches to a physically close upper layer node. A d-ary update message propagation tree (UMPT) is dynamically built upon the upper layer for propagating the updated contents. As a result, the tree structure does not need to be maintained all the time, saving a lot of cost. Through theoretical analyses and comprehensive simulations, we examine the efficiency and scalability of this design. The results show that, compared with previous designs, especially locality-ignorant ones, our approach is able to reduce the cost by about 25-67 percent. View full abstract»

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  • Interference-Aware Joint Routing and TDMA Link Scheduling for Static Wireless Networks

    Publication Year: 2008 , Page(s): 1709 - 1726
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (919 KB) |  | HTML iconHTML  

    We study efficient interference-aware joint routing and TDMA link scheduling for a multihop wireless network to maximize its throughput. Efficient link scheduling can greatly reduce the interference effect of close-by transmissions. Unlike the previous studies that often assume a unit disk graph model, we assume that different terminals could have different transmission ranges and interference ranges. In our model, a communication link may not exist due to barriers or is not used by a predetermined routing protocol. Using a mathematical formulation, we develop interference aware joint routing and TDMA link schedulings that optimize the networking throughput subject to various constraints. Our linear programming formulation will find a flow routing whose achieved throughput (or fairness) is at least a constant fraction of the optimum. Then, by assuming known link capacities and link traffic loads, we study link scheduling under the RTS/CTS interference model and the protocol interference model with fixed transmission power. For both models, we present both efficient centralized and distributed algorithms that use time slots within a constant factor of the optimum. We also present efficient distributed algorithms whose performances are still comparable with optimum, but with much less communications. Our theoretical results are corroborated by extensive simulation studies. View full abstract»

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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