Browsing by Subject "Natural sciences computing"

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    A comparison of logical and physical parallel I/O patterns
    (SAGE Publications Inc., 1998) Simitci, H.; Reed, D. A.
    Although there are several extant studies of parallel scientific application request patterns, there is little experimental data on the correlation of physical I/O patterns with application I/O stimuli. To understand these correlations, the authors have instrumented the SCSI device drivers of the Intel Paragon OSF/1 operating system to record key physical I/O activities, and have correlated this data with the I/O patterns of scientific applications captured via the Pablo analysis toolkit. This analysis shows that disk hardware features profoundly affect the distribution of request delays and that current parallel file systems respond to parallel application I/O patterns in nonscalable ways.
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    Multi-level direct K-way hypergraph partitioning with multiple constraints and fixed vertices
    (Academic Press, 2008-05) Aykanat, Cevdet; Cambazoglu, B. B.; Uçar, B.
    K-way hypergraph partitioning has an ever-growing use in parallelization of scientific computing applications. We claim that hypergraph partitioning with multiple constraints and fixed vertices should be implemented using direct K-way refinement, instead of the widely adopted recursive bisection paradigm. Our arguments are based on the fact that recursive-bisection-based partitioning algorithms perform considerably worse when used in the multiple constraint and fixed vertex formulations. We discuss possible reasons for this performance degradation. We describe a careful implementation of a multi-level direct K-way hypergraph partitioning algorithm, which performs better than a well-known recursive-bisection-based partitioning algorithm in hypergraph partitioning with multiple constraints and fixed vertices. We also experimentally show that the proposed algorithm is effective in standard hypergraph partitioning. © 2007 Elsevier Inc. All rights reserved.