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Parallel, Distributed and Network-Based Processing, 2007. PDP '07. 15th EUROMICRO International Conference on

Date 7-9 Feb. 2007

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  • 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing - Cover

    Page(s): c1
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  • 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing - Title

    Page(s): i - iii
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  • 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing - Copyright

    Page(s): iv
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  • 15th EUROMICRO International Conference on Parallel, Distributed and Network-Based Processing - Table of contents

    Page(s): v - x
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  • Program Chairs Preface

    Page(s): xi
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  • Program Committee

    Page(s): xii
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  • Special Sessions Committees

    Page(s): xiii
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  • Organizing Committee

    Page(s): xv
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  • Additional reviewers

    Page(s): xvi
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  • Using Grids for Exploiting Data Abundance in Science

    Page(s): xvii
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  • Optimal Kernels to Optimal Solutions: Algorithm and Software Issues in Solver Development

    Page(s): xviii
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    Summary form only given. Computer modeling and simulation efforts are most useful when they can provide an optimal solution to a problem. Toward this goal we need a vertical hierarchy of algorithmic capabilities and software tools, all of which must work together to make optimal solutions possible. In this presentation we discuss efforts in the Trilinos project to enable optimal solutions for scientific and engineering applications. We discuss how the goal of optimal solutions drives requirements not only for good optimization algorithms but also ever faster and more robust forward solvers and scalable kernels, as well as an abstraction layer to couple solver components. View full abstract»

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  • Grid Multi-Resolution Docking

    Page(s): 3 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB) |  | HTML iconHTML  

    Detailed knowledge of macromolecular structure is essential for the understanding of how the cellular machines work. Rigid body fitting is the common way to interpret the information contained in a 3D electron microscope (3DEM) medium-low resolution map in terms of its available atomic structural components. This fitting process, termed multi-resolution docking, consists in localizing atomic resolution structures into the 3DEM map by means of an exhaustive search of all possible relative rotations and translations. This exhaustive search is a highly computing demanding process and several search queries are also typically needed to select good fitting structures. Here, we present a novel and efficient Grid approach for performing these docking searches. This approach has been designed over the Gridway meta-scheduler. Results showing the high efficiency achieved are discussed together with the corresponding analysis of the performance obtained. The experiments were conducted on a Grid testbed built up from resources inside EGEE (LCG version of the pre-WS Globus components), the European production-level grid infrastructure, and resources from a research testbed based on the Globus Toolkit 4 (Web services components) View full abstract»

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  • Improving the Development Process for CSE Software

    Page(s): 11 - 17
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    Scientific and engineering programming has been around since the beginning of computing, often being the driving force for new system development and innovation. At the same time a continual focus on new modeling capabilities, and some apparent cultural issues, find software processes for many computational science and engineering (CSE) software projects lacking. Certainly there are notable exceptions, but our experience has been that CSE software projects, although committed to writing high-quality software, have few if any formal software processes and tools in place, and are often unaware of formal software quality assurance (SQA) concepts. Presently, increasing complexity of applications and a broad push to certify computations are dictating a higher standard for CSE software quality; it is no longer sufficient to claim to write high quality software. However, traditional software development models can be impractical for CSE projects to implement. Despite this, CSE software teams can benefit by implementing valuable SQA processes and tools. In this paper we outline some the processes and tools that are successfully used by the Trilinos Project. These tools and processes have been useful not only in increasing verifiable software quality, but also have improved overall software quality, and the development experience in general View full abstract»

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  • A New Parallel Sorting Algorithm based on Odd-Even Mergesort

    Page(s): 18 - 22
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (235 KB) |  | HTML iconHTML  

    This paper describes a new parallel sorting algorithm, derived from the odd-even mergesort algorithm, named "partition and concurrent merging" (PCM). The proposed algorithm is based on a divide-and-conquer strategy. First, the data sequence to be sorted is decomposed in several pieces that are sorted in parallel using Quicksort. After that, all pieces are merged using a recursive procedure to obtain the final sorted sequence. In each iteration of this procedure pairs of sequence pieces are selected and sorted concurrently. The paper analyzes the computational complexity of the new algorithm and compares it with that of other well-known parallel sorting algorithms. We implemented the PCM algorithm on a SGI Origin2000 multiprocessor using OpenMP, sorting different benchmark sets of data sequences. Experimental results are compared with those of the Quicksort sequential algorithm and parallel implementations of other sorting algorithms, obtaining that our proposal outperforms the other solutions View full abstract»

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  • A Grid-based Parallel Approach of the Multi-Objective Branch and Bound

    Page(s): 23 - 30
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (132 KB) |  | HTML iconHTML  

    The branch and bound (B&B) algorithm is one of the most used methods to solve in an exact way combinatorial optimization problems. This article focuses on the multi-objective version of this algorithm, and proposes a new parallel approach adapted to grid computing systems. This approach addresses several issues related to the characteristics of the algorithm itself and the properties of grid computing systems. Validation is performed by experimenting the approach on a bi-objective flow-shop problem instance that has never been solved exactly. Solving this instance, after several days of computation on a grid of more than 1000 processors, belonging to 7 distinct clusters, the obtained results prove the efficiency of the proposed approach View full abstract»

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  • Improving Search in Peer-to-Peer Literature Sharing Systems via Semantic Small World

    Page(s): 31 - 38
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (298 KB) |  | HTML iconHTML  

    Efficient search for unstructured peer-to-peer information retrieval systems is a challenging problem. This paper proposes a semantic overlay based on the small world phenomenon that facilitates efficient search for information retrieval in unstructured P2P systems. In the semantic overlay, each node maintains a number of short-range links which are semantically similar to the node, together with a small collection of long-range links that help increase recall rate of information retrieval as well as reduce network traffic. In this paper we present how to construct and maintain a semantic small world overly, and the search strategy utilizing the above semantic overlay. Experimental results show that our model can improve performance by 150% compared to Gnutella and by up to 50% compared to the Interest-based model, a similar shortcut-based search technique View full abstract»

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  • Scheduling Communication Requests Traversing a Switch: Complexity and Algorithms

    Page(s): 39 - 46
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (5706 KB) |  | HTML iconHTML  

    In this paper, we study the problem of scheduling file transfers through a switch. This problem is at the heart of a model often used for large grid computations, where the switch represents the core of the network interconnecting the various clusters that compose the grid. We establish several complexity results, and we introduce and analyze various algorithms, from both a theoretical and a practical perspective View full abstract»

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  • An Effective Starvation Avoidance Mechanism to Enhance the Token Coherence Protocol

    Page(s): 47 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    Shared-memory multiprocessors are becoming to be formed by an increasingly larger number of nodes. In these systems, implementing cache coherence is a key issue. Token coherence is a low latency cache coherence protocol that avoids indirection for cache-to-cache misses and which does not require a totally-ordered interconnect. When races are rare, the protocol performs well thanks to the performance policy. Unfortunately, some medium/large systems and some applications that often access the same data simultaneously make races more common. As a result, the protocol does not perform as well as it could because it uses the persistent request mechanism to prevent starvation. This mechanism is too slow and inflexible because it overrides the performance policy. In consequence, the protocol slows down the system and does not take advantage of the flexibility and speed of the common case. We propose a new mechanism, namely priority requests, which replaces the persistent request one. Our mechanism solves races, while still respecting the performance policy, simply by ordering and giving a higher priority to requests suffering from starvation. Thus, our mechanism handles the tokens more efficiently and reduces the network traffic View full abstract»

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  • Boosting Ethernet Performance by Segment-Based Routing

    Page(s): 55 - 62
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (182 KB) |  | HTML iconHTML  

    Ethernet is turning out to be a cost-effective solution for building cluster networks offering compatibility, simplicity, high bandwidth, scalability and a good performance-to-cost ratio. Nevertheless, Ethernet still makes inefficient use of network resources (links) and suffers from long failure recovery time due to the lack of a suitable routing algorithm. In this paper we embed an efficient routing algorithm into 802.3 Ethernet technology, making it possible to use off-the-shelf equipment to build high-performance and cost-effective Ethernet clusters, with an efficient use of link bandwidth and with fault tolerant capabilities. The algorithm, referred to as segment-based routing (SR), is a deterministic routing algorithm that achieves high performance without the need for virtual channels (not available in Ethernet). Moreover, SR is topology agnostic, meaning it can be applied to any topology, and tolerates any combination of faults derived from the original topology when combined with static reconfiguration. Through simulations we verify an overall improvement in throughput by a factor of 1.2 to 10.0 when compared to the conventional Ethernet routing algorithm, the spanning tree protocol (STP), and other topology agnostic routing algorithms such as Up*/Down* and tree-based turn-prohibition, the last one being recently proposed for Ethernet View full abstract»

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  • Activity Pre-Scheduling in Grid Workflows

    Page(s): 63 - 71
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (310 KB) |  | HTML iconHTML  

    Grid computing is becoming a prominent field of interest for distributed systems. The capability to support resource sharing between different organizations and the high level of performance are noteworthy features. However, to define, deploy and execute grid applications require significant design effort and complex resource coordination, which can be alleviated by using workflow management systems. This technology is more and more adopted in distributed systems and grids since it ensures easiness and flexibility at design-time and performance and dynamicity at run-time. This paper gives a contribution to performance improvements of workflow by presenting a technique to exploit fine-grained concurrency at run-time. The technique is implemented in a workflow enactment service that dynamically optimizes process execution limiting the design effort of application developers View full abstract»

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  • Differentiated Quality of Service for e-Commerce Applications through Connection Scheduling based on System-Level Thread Priorities

    Page(s): 72 - 76
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (186 KB) |  | HTML iconHTML  

    The e-commerce Web sites receive a great and varied number of visitors every day. These visitors share the application server's limited resources and when there are too many clients connecting to the Web site, it is possible that they hinder between them, even to overload the application server. These visitors can be divided in different categories, depending on their importance from site viewpoint. Considering the importance that in these Web sites some client connections (e.g. buyers' connections) finish successfully before other connections, in this paper we propose a mechanism to provide different quality of service to the different client categories by assigning different priorities to the threads attending the connections. After observing that Java thread priorities are only applied within the JVM, and moreover, these priorities do not reach the O.S. threads, we propose to schedule threads using the Linux Real Time priorities. Our results demonstrate that different quality of service classes can be supported using this mechanism View full abstract»

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  • Communication Study and Implementation Analysis of Parallel Asynchronous Iterative Algorithms on Message Passing Architectures

    Page(s): 77 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (179 KB) |  | HTML iconHTML  

    The implementation of parallel asynchronous iterative algorithms on message passing architectures is considered. Several issues related to communication via message passing interfaces or libraries such as MPI-1, MPI-2, PVM or SHMEM are discussed in this survey paper. Practical implementations are proposed View full abstract»

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  • Towards On-Demand Ubiquitous Metascheduling on Computational Grids

    Page(s): 84 - 90
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1696 KB) |  | HTML iconHTML  

    Grid computing technologies are mature enough to be successfully applied to computationally intensive scientific applications. However, the current process of applying grid computing to them is still hard and difficult for the least experienced users. In this paper we describe the adaptations made to the GMarte metascheduling framework in order to provide an ubiquitous access to its functionality as an efficient resource broker for the execution of tasks on computational grids. A metascheduling component accessible by only means of a Java-enabled Web browser has been developed, requiring almost zero configuration by the client. This approach has enabled to produce a generic multi-platform metascheduler which can be automatically deployed in the clients interested in resource brokering on computational grids based on the Globus Toolkit View full abstract»

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  • A Performance Model for Stream-based Computations

    Page(s): 91 - 96
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (199 KB) |  | HTML iconHTML  

    Component-based grid applications have complex deployment models. Performance-sensitive decisions should be taken by automatic tools. Such tools must match developer knowledge on component performance with QoS requirements on the applications, in order to find deployment plans that satisfy a service level agreement (SLA). This paper presents a steady state performance model that can be employed to reason about and automatically map stream-based component programs View full abstract»

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  • pDomus: a prototype for Cluster-oriented Distributed Hash Tables

    Page(s): 97 - 104
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1551 KB) |  | HTML iconHTML  

    The Domus architecture for distributed hash tables (DHTs) is specially designed to support the concurrent deployment of multiple and heterogeneous DHTs, in a dynamic shared-all cluster environment. The execution model is compatible with the simultaneous access of several distributed/parallel client applications to the same or different running DHTs. Support to distributed routing and storage is dynamically configurable per node, as a function of applications requirements, node base resources and the overall cluster communication, memory and storage usage. pDomus is a prototype of Domus that creates an environment where to evaluate the model embedded concepts and planned features. In this paper, we present a series of experiments conduced to obtain figures of merit i) for the performance of basic dictionary operations, and ii) for the storage overhead resulting from several storage technologies. We also formulate a ranking formula that takes into account access patterns of clients to DHTs, to objectively select the most adequate storage technology, as a valuable metric for a wide range of application scenarios. Finally, we also evaluate client applications and services scalability, for a select dictionary operation. Results of the overall evaluation are promising and a motivation for further work View full abstract»

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