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International symposium on parallel and distributed processing (IPDPS)

作者： R. Collins F. Alegre Xiaotong Zhuang S. Pande College of Computing Georgia Institute of Technology Atlanta GA USA

ISBN: (纸本)9781424400546

Modern network processors support high levels of parallelism in packet processing by supporting multiple threads that execute on a micro-engine. Threads switch context upon encountering long latency memory accesses and this way the parallelism and memory access can be overlapped. Context switches in the typical network processor architectures such as the IXP are designed to be very fast. However, the low overhead is partly achieved by leaving register management to programs, with minimal support from the hardware. The complexity of the multi-engine, multi-threaded environment makes manual register management a daunting task, which is better left to a compiler. However, a purely static analysis is unable to achieve full utilization of the register file due to conservative estimates of liveness. A register that is live across a context switch point must be considered live for the duration of all other threads, and so it must be assumed to be unavailable to other threads. In addition, aliasing further reduces the effectiveness of static analysis. The net effect is a large number of idle cycles that are still present after static optimization. We propose a dynamic solution that requires minimal software and hardware support. On the software side, we take a pre-allocated binary file and annotate the potential context switch instructions with information about the dead registers. On the hardware side, we try to rename the transfer registers and addresses to dead general purpose registers and update the usage of registers. We then replace the long-latency memory instructions with fast move instructions in the architecture using the dynamic context. The results show up to 51% reduction in idle cycles and up to H% increase in the throughput for hand coded applications on Intel IXP 1200 network processor

关键词： Dynamic compiler Registers Yarn Switches Hardware parallel processing Delay Programming profession Program processors Computer network management

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Assembling genomes on large-scale parallel computers 06

Assembling genomes on large-scale parallel computers

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International symposium on parallel and distributed processing (IPDPS)

作者： A. Kalyanaraman S.J. Emrich P.S. Schnable S. Aluru Department of Electrical and Computer Engineering Iowa State University Ames IA USA Bioinformatics and Computational Biology Program Iowa State University Ames IA USA Iowa State University Ames IA US Dept. of Electr. & Comput. Eng. Iowa State Univ. Ames IA USA

ISBN: (纸本)9781424400546

Assembly of large genomes from tens of millions of short genomic fragments is computationally demanding requiring hundreds of gigabytes of memory and tens of thousands of CPU hours. New gene-enrichment sequencing strategies are expected to further exacerbate this situation. In this paper, we present a massively parallel genome assembly framework. The unique features of our approach include space-efficient and on-demand algorithms that consume only linear space, and heuristic strategies that reduce the number of expensive pairwise sequence alignments while maintaining assembly quality. As part of the ongoing efforts in maize genome sequencing, we applied our assembly framework to the largest available collection of maize genomic data. We report the partitioning of more than 1.6 million fragments of over 1.25 billion nucleotides total size into genomic islands in 2 hours on 1,024 processors of an IBM BlueGene/L supercomputer.

关键词： Assembly Genomics Bioinformatics Large-scale systems Concurrent computing Sequences DNA Organisms Biology computing Biological cells

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Trust overlay networks for global reputation aggregation in P2P grid computing 06

Trust overlay networks for global reputation aggregation in ...

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International symposium on parallel and distributed processing (IPDPS)

作者： Runfang Zhou Kai Hwang University of Southern California USA

ISBN: (纸本)9781424400546

This paper presents a new approach to trusted grid computing in a peer-to-peer (P2P) setting. Trust and security are essential to establish lasting working relationships among the peers. A P2P reputation system collects peer trust scores and aggregates them to yield a global reputation. We use a new trust overlay network (TON) to model the trust relationships among the peers. After analyzing the eBay transaction trace data, we discover a power-law distribution in user feedbacks. We develop a new reputation system, PowerTrust, to leverage power-law feedback characteristics. The PowerTrust system is built with locality-preserving hash functions and a lookahead random walk strategy. Dynamic system reconfiguration is enabled by the use of power nodes with well-established reputations. Through P2P simulation experiments on distributed file sharing and grid parameter-sweeping applications (PSA), we demonstrate the PowerTrust advantages in fast reputation convergence and accurate ranking of peer reputations. We report performance results with enhanced P2P query success rate, shortened job makespan, and increased job success rate in scalable P2P grid applications

关键词： Intelligent networks Grid computing Peer to peer computing distributed computing Feedback Power system modeling Power system management Web services Security Computer architecture

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Shared receive queue based scalable MPI design for InfiniBand clusters 06

Shared receive queue based scalable MPI design for InfiniBan...

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International symposium on parallel and distributed processing (IPDPS)

作者： S. Sur Lei Chai Hyun-Wook Jin D.K. Panda Network-Based Computing Laboratory The Ohio State University USA

ISBN: (纸本)9781424400546

Clusters of several thousand nodes interconnected with InfiniBand, an emerging high-performance interconnect, have already appeared in the Top 500 list. The next-generation InfiniBand clusters are expected to be even larger with tens-of-thousands of nodes. A high-performance scalable MPI design is crucial for MPI applications in order to exploit the massive potential for parallelism in these very large clusters. MVAPICH is a popular implementation of MPI over InfiniBand based on its reliable connection oriented model. The requirement of this model to make communication buffers available for each connection imposes a memory scalability problem. In order to mitigate this issue, the latest InfiniBand standard includes a new feature called shared receive queue (SRQ) which allows sharing of communication buffers across multiple connections. In this paper, we propose a novel MPI design which efficiently utilizes SRQs and provides very good performance. Our analytical model reveals that our proposed designs take only 1/10 th the memory requirement as compared to the original design on a cluster sized at 16,000 nodes. Performance evaluation of our design on our 8-node cluster shows that our new design was able to provide the same performance as the existing design while requiring much lesser memory. In comparison to tuned existing designs our design showed a 20% and 5% improvement in execution time of NAS Benchmarks (Class A) LU and SP, respectively. The high performance Linpack was able to execute a much larger problem size using our new design, whereas the existing design ran out of memory

关键词： Sun Large-scale systems Computer networks Laboratories Computer science parallel processing Scalability Communication standards Analytical models Radio access networks

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Toward reliable and efficient message passing software through formal analysis

Toward reliable and efficient message passing software throu...

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International symposium on parallel and distributed processing (IPDPS)

作者： G. Gopalakrishnan R. Kirby School of Computing University of Utah Salt Lake UT USA

The quest for high performance drives parallel scientific computing software design. Well over 60% of the high-performance computing (HPC) community writes programs using the MPI library; to gain performance, they are known to perform many manual optimizations. Even tools that accept high level descriptions often generate MPI code, due to its eminent portability. However, since the overall performance of a program does not usually port (due to variations in the target architecture, cluster size, etc.), manual changes to the code are inevitable in today's approaches to MPI programming and optimization. This, together with the vastness and evolving nature of the MPI standard, and the innate complexity of concurrent programming introduces costly bugs. Our research addresses these challenges through specific efforts in the following broad areas: (i) high level expression of the parallel algorithm and compilation thereof into optimized MPI programs, (ii) optimizations of user-written detailed MPI programs through localized transformations such as barrier removal, (iii) formal modeling of complex communication standards, such as the MPI-2 standard and a facility for answering putative queries (this need arises when standard documents are impossibly difficult to manually study in order to answer questions that are not explicitly addressed in the standard), (iv) formal modeling of new (and hence relatively less well understood) features of communication libraries, such as the one-sided communication facility of MPI-2, and (v) formal modeling of intricate control algorithms in these libraries such as the progress engine for TCP and/or shared memory in MPICH2 (a formal model can explicate commonalities, help formally verify, as well as help create better future implementations). Our research gains focus through numerous collaborations

关键词： Message passing Communication standards Scientific computing Software design High performance computing Software libraries Performance gain Computer bugs parallel algorithms Communication system control

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Centralized versus distributed schedulers for multiple bag-of-task applications 06

Centralized versus distributed schedulers for multiple bag-o...

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International symposium on parallel and distributed processing (IPDPS)

作者： O. Beaumont L. Carter J. Ferrante A. Legrand L. Marchal Y. Robert Laboratoire LaBRI CNRS-INRIA France Department of Computer Science and Engineering University of California San Diego USA Laboratoire ID-IMAG CNRS-INRIA Grenoble France Laboratoire LIP CNRS-INRIA École Normale Supérieure de Lyon France

ISBN: (纸本)9781424400546

Multiple applications that execute concurrently on heterogeneous platforms compete for CPU and network resources. In this paper, we consider the problem of scheduling applications to ensure fair and efficient execution on a distributed network of processors. We limit our study to the case where communication is restricted to a tree embedded in the network, and the applications consist of a large number of independent tasks that originate at the tree's root. The tasks of a given application all have the same computation and communication requirements, but these requirements can vary for different applications. Each application is given a weight that quantifies its relative value. The goal of scheduling is to maximize throughput while executing tasks from each application in the same ratio as their weights. We can find the optimal asymptotic rates by solving a linear program that expresses all necessary problem constraints, and we show how to construct a periodic schedule. For single-level trees, the solution is characterized by processing tasks with larger communication-to-computation ratios at children with larger bandwidths. For multi-level trees, this approach requires global knowledge of all application and platform parameters. For large-scale platforms, such global coordination by a centralized scheduler may be unrealistic. Thus, we also investigate decentralized schedulers that use only local information at each participating resource. We assess their performance via simulation, and compare to a centralized solution obtained via linear programming. The best of our decentralized heuristics achieves the same performance on about two-thirds of our test cases, but is far worse in a few cases. While our results are based on simplistic assumptions and do not explore all parameters (such as buffer size), they provide insight into the important question of fairly and optimally co-scheduling heterogeneous applications on heterogeneous grids

关键词： Processor scheduling Application software Throughput Bandwidth Central processing Unit Computer networks Computer science Large-scale systems Linear programming Testing

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distributed coloring in O/spl tilde/(/spl radic/(log n)) bit rounds

Distributed coloring in O/spl tilde/(/spl radic/(log n)) bit...

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International symposium on parallel and distributed processing (IPDPS)

作者： K. Kothapalli C. Scheideler M. Onus C. Schindelhauer Department of Computer Science Johns Hopkins University Baltimore MD USA Computer Science Department Technische Universität München Garching Germany Department of Computer Science Arizona State University Tempe AZ USA Heinz Nixdorf Institute and Computer Science Department University of Paderborn Paderborn Germany

We consider the well-known vertex coloring problem: given a graph G, find a coloring of the vertices so that no two neighbors in G have the same color. It is trivial to see that every graph of maximum degree Delta can be colored with Delta + 1 colors, and distributed algorithms that find a (Delta + 1)-coloring in a logarithmic number of communication rounds, with high probability, are known since more than a decade. This is in general the best possible if only a constant number of bits can be sent along every edge in each round. In fact, we show that for the n-node cycle the bit complexity of the coloring problem is Omega(log n). More precisely, if only one bit can be sent along each edge in a round, then every distributed coloring algorithm (i.e., algorithms in which every node has the same initial state and initially only knows its own edges) needs at least Omega(log n) rounds, with high probability, to color the cycle, for any finite number of colors. But what if the edges have orientations, i.e., the end-points of an edge agree on its orientation (while bits may still flow in both directions)? Does this allow one to provide faster coloring algorithms? Interestingly, for the cycle in which all edges have the same orientation, we show that a simple randomized algorithm can achieve a 3-coloring with only O(radic(log n)) rounds of bit transmissions, with high probability (w.h.p.). This result is tight because we also show that the bit complexity of coloring an oriented cycle is Omega(radic(log n)), with high probability, no matter how many colors are allowed. The 3-coloring algorithm can be easily extended to provide a (Delta + 1)-coloring for all graphs of maximum degree Delta in O(radic(log n)) rounds of bit transmissions, w.h.p., if Delta is a constant, the edges are oriented, and the graph does not contain an oriented cycle of length less than radic(log n). Using more complex algorithms, we show how to obtain an O(Delta)-coloring for arbitrary oriented graphs of

关键词： Computer science distributed computing distributed algorithms Wireless networks Contracts Large-scale systems Information systems Processor scheduling Resource management Routing

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Notice of Violation of ieee Publication Principles: A New Predictive Mechanism Based on Artificial Neural Network

Notice of Violation of IEEE Publication Principles: A New Pr...

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International Conference on Computational Intelligence and Security

作者： Dong Li Wenqiang Yu School of Engineering and Technology Shandong University of Technology Zibo Shandong China

Notice of Violation of ieee Publication Principles "A New Predictive Mechanism Based on Artificial Neural Network," by Dong Li and Wenqiang Yu, in the proceedings of the International Conference on Computational Intelligence and Security, Nov. 2006 pp. 333-338 After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of ieee's Publication Principles. This paper is a near verbatim copy of the papers cited below. The original text was copied without attribution. Due to the nature of this violation, reasonable effort should be made to remove all past references to this paper, and future references should be made to the following article: "A Neural Network Based Predictive Mechanism for Available Bandwidth," by Alaknantha Eswaradass, Xian-He Sun and Ming Wu, in the proceedings of the 19th ieee International parallel and distributed processing symposium, April 2005 Many recent developments of computer technology, such as Web services, Grid, peer-to-peer, and mobile computing, are network-based computing. Their applicability depends on the availability of the underlying network bandwidth. However, network resources are shared and the available network bandwidth varies with time. There is no satisfactory solution available for network performance predictions. This lack of prediction limits the applicability of network-based computing, especially for grid computing where concurrent remote processing is essential. In this paper, we propose an artificial neural network (ANN) based approach for network performance prediction. The ANN mechanism has been tested on classical trace files and compared with the well-known system NWS (Network Weather Service) for performance. Experimental results show the ANN approach always provides an improved prediction over that of NWS

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parallel and distributed processing and Applications - third International symposium, ISPA 2005, proceedings

Parallel and Distributed Processing and Applications - Third...

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3rd International symposium on parallel and distributed processing and Applications, ISPA 2005

ISBN: (纸本)3540297693

The proceedings contain 111 papers. The topics discussed include: data structures and algorithms for packet forwarding and classification;towards peta-bit photonic networks;modeling and analysis of a parallel nested loop join on cluster architectures;scheduling efficiently for irregular load distributions in a large-scale cluster;on service-oriented network measurement architecture with mobile agent;design and evaluation of network-bandwidth-based parallel replication algorithm;replicating multithreaded web services;cache management for discrete processor architectures;aggressive loop fusion for improving locality and parallelism;adaptive parallel ant colony optimization;a fast and scalable conflict detection algorithm for packet classifiers;and a new data fusion model of intrusion detection-IDSFP.

关键词： distributed database systems

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parallel and distributed processing and Applications - third International symposium, ISPA 2005, proceedings: Preface

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2005年 3758 LNCS卷 V页

作者： Pan, Yi Chen, Daoxu

No abstract available

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