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## Performance results of running parallel applications on the InteGrade

CACERES, E. N.; MONGELLI, H.; LOUREIRO, L.; NISHIBE, C.; SONG, S. W.
Fonte: JOHN WILEY & SONS LTD Publicador: JOHN WILEY & SONS LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.21%
The InteGrade middleware intends to exploit the idle time of computing resources in computer laboratories. In this work we investigate the performance of running parallel applications with communication among processors on the InteGrade grid. As costly communication on a grid can be prohibitive, we explore the so-called systolic or wavefront paradigm to design the parallel algorithms in which no global communication is used. To evaluate the InteGrade middleware we considered three parallel algorithms that solve the matrix chain product problem, the 0-1 Knapsack Problem, and the local sequence alignment problem, respectively. We show that these three applications running under the InteGrade middleware and MPI take slightly more time than the same applications running on a cluster with only LAM-MPI support. The results can be considered promising and the time difference between the two is not substantial. The overhead of the InteGrade middleware is acceptable, in view of the benefits obtained to facilitate the use of grid computing by the user. These benefits include job submission, checkpointing, security, job migration, etc. Copyright (C) 2009 John Wiley & Sons, Ltd.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP[2004/08928-3]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[55.0895/07-8]; CNPq[30.5362/06-2]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[30.2942/04-1]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[62.0123/04-4]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[48.5460/06-8]; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq[62.0171/06-5]; FUNDECT[41/100.115/2006]; FUNDECT

## Desenvolvimento de modelos e algoritmos sequenciais e paralelos para o planejamento da expansão de sistemas de transmissão de energia elétrica; Development of mathematical models, sequential and parallel algorithms for transmission expansion planning

Sousa, Aldir Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
56.28%
O principal objetivo deste estudo é propor uma nova metodologia para lidar com o problema de Planejamento da Expansão de Redes de Transmissão de Energia Elétrica com Múltiplos Cenários de Geração (PERTEEG). Com a metodologia proposta neste trabalho almeja-se construir planos de expansão de redes de transmissão de energia elétrica que sejam capazes de, no menor custo de investimento possível, satisfazer às novas exigências dos sistemas elétricos modernos, tais como construção de redes de transmissão livres de congestionamento e robustas à incerteza em relação aos cenários de geração futuros. Através de estudos realizados na literatura do problema, verificou-se que novos modelos e metodologias de abordagem do PERTEEG se fazem necessários. Ao se modelar o PERTEEG visando construir redes de transmissão que contornem as incertezas em relação aos cenários de geração futuros e concomitantemente minimizar o custo de investimento para a expansão do sistema, o planejador se depara com um problema de otimização multiobjetivo. Existem na literatura da pesquisa operacional diversos algoritmos que visam lidar com problemas multiobjetivos. Nesta tese, foram aplicados dois desses algoritmos: Nondominated Sorting Genetic Algorithms-II (NSGA-II) e SPEA2: Strength Pareto Evolutionary Algorithm (SPEA2). Em primeira análise...

## Parallel programming in biomedical signal processing

Chorão, Ricardo Daniel Domingos
Relevância na Pesquisa
56.27%
Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica; Patients with neuromuscular and cardiorespiratory diseases need to be monitored continuously. This constant monitoring gives rise to huge amounts of multivariate data which need to be processed as soon as possible, so that their most relevant features can be extracted. The field of parallel processing, an area from the computational sciences, comes naturally as a way to provide an answer to this problem. For the parallel processing to succeed it is necessary to adapt the pre-existing signal processing algorithms to the modern architectures of computer systems with several processing units. In this work parallel processing techniques are applied to biosignals, connecting the area of computer science to the biomedical domain. Several considerations are made on how to design parallel algorithms for signal processing, following the data parallel paradigm. The emphasis is given to algorithm design, rather than the computing systems that execute these algorithms. Nonetheless, shared memory systems and distributed memory systems are mentioned in the present work. Two signal processing tools integrating some of the parallel programming concepts mentioned throughout this work were developed. These tools allow a fast and efficient analysis of long-term biosignals. The two kinds of analysis are focused on heart rate variability and breath frequency...

## Designing Efficient Parallel Algorithms for Graph Problems

Liang, Weifa
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
EN
Relevância na Pesquisa
66.26%
Graph algorithms are concerned with the algorithmic aspects of solving graph problems. The problems are motivated from and have application to diverse areas of computer science, engineering and other disciplines. Problems arising from these areas of application are good candidates for parallelization since they often have both intense computational needs and stringent response time requirements. Motivated by these concerns, this thesis investigates parallel algorithms for these kinds of graph problems that have at least one of the following properties: the problems involve some type of dynamic updates; the sparsification technique is applicable; or the problems are closely related to communications network issues. The models of parallel computation used in our studies are the Parallel Random Access Machine (PRAM) model and the practical interconnection network models such as meshes and hypercubes. ¶ ...; yes

## Designing Parallel Algorithms for SMP Clusters; Entwurf von Parallelen Algorithmen für SMP Clusters

Schmollinger, Martin
Tipo: Dissertação
EN
Relevância na Pesquisa
66.28%
In the following thesis, we observe methods for designing and optimizing parallel algorithms for SMP clusters. This particular architecture for parallel computers combines two different concepts. SMP cluster consist of computing nodes that are shared-memory systems, because the processors have access to common resources and especially to the local memory system. Hence, the processors within the same node are capable to communicate and synchronize using the shared-memory. An interconnection network connects the nodes. Communication and synchronization of processors from different nodes is done over this network and thus, correspond to a distributed memory system. In the first place, this organization leads to a parallel hierarchy, because parallelism is involved within and between the nodes. Secondly, a hierarchy is created concerning communication. In general, communication within a node is faster than communication between the nodes due to the use of shared-memory. Therefore, there are at least two levels of hierarchy. Due to modern trends like hierarchical interconnection structures, Metacomputing technology, where several parallel machines are connected, or Grid computing technology that use the Internet to unify distributed computing resources in the whole world...

## Parallel algorithms and architectures for subspace based channel estimation for CDMA communication systems

Sengupta, Chaitali; Kota, Kishore; Cavallaro, Joseph R.; Sengupta, Chaitali; Kota, Kishore; Cavallaro, Joseph R.
Tipo: Conference paper
ENG
Relevância na Pesquisa
66.26%
Conference Paper; This paper presents an overview and results from an ongoing research project to study parallel algorithms for the acquisition of Code Division Multiple Access (CDMA) communication signals. The goal of this research isto evaluate a class of related algorithms and architectures for the acquisition problem and map them onto parallel architectures containing DSPs. The algorithms used are generally termed subspace-based algorithms, since they involve computation of subspaces of the vector space spanned by certain observation vectors. This paper presents results from some preliminary implementations of such a subspace-based algorithm on the Texas Instruments TMS320C40 Parallel Processing Development System.

## Parallel algorithms in linear algebra

Brent, Richard P
Tipo: Working/Technical Paper Formato: 166298 bytes; 356 bytes; application/pdf; application/octet-stream
EN_AU
Relevância na Pesquisa
56.18%
This paper provides an introduction to algorithms for fundamental linear algebra problems on various parallel computer architectures, with the emphasis on distributed-memory MIMD machines. To illustrate the basic concepts and key issues, we consider the problem of parallel solution of a nonsingular linear system by Gaussian elimination with partial pivoting. This problem has come to be regarded as a benchmark for the performance of parallel machines. We consider its appropriateness as a benchmark, its communication requirements, and schemes for data distribution to facilitate communication and load balancing. In addition, we describe some parallel algorithms for orthogonal (QR) factorization and the singular value decomposition (SVD).; no

## Algoritmos paralelos para alocação e gerência de processadores em máquinas multiprocessadoras hipercúbicas; Parallel algorithms for processor allocation in hypercubes

De Rose, Cesar Augusto Fonticielha
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
56.39%

## Efficient parallel algorithms for elastic-plastic finite element analysis

Ding, Zhongwen (Kevin); Qin, Qing Hua; Cardew-Hall, Michael; Kalyanasundaram, Shankar
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.18%
This paper presents our new development of parallel finite element algorithms for elastic-plastic problems. The proposed method is based on dividing the original structure under consideration into a number of substructures which are treated as isolated fi

## Simulating Parallel Algorithms in the MapReduce Framework with Applications to Parallel Computational Geometry

Goodrich, Michael T.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.24%
In this paper, we describe efficient MapReduce simulations of parallel algorithms specified in the BSP and PRAM models. We also provide some applications of these simulation results to problems in parallel computational geometry for the MapReduce framework, which result in efficient MapReduce algorithms for sorting, 1-dimensional all nearest-neighbors, 2-dimensional convex hulls, 3-dimensional convex hulls, and fixed-dimensional linear programming. For the case when reducers can have a buffer size of $B=O(n^\epsilon)$, for a small constant $\epsilon>0$, all of our MapReduce algorithms for these applications run in a constant number of rounds and have a linear-sized message complexity, with high probability, while guaranteeing with high probability that all reducer lists are of size $O(B)$.; Comment: Version of paper appearing in MASSIVE 2010

## Improved bounds and parallel algorithms for the Lovasz Local Lemma

Haeupler, Bernhard; Harris, David G.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.21%
The Lovasz Local Lemma (LLL) is a cornerstone principle in the probabilistic method of combinatorics, and a seminal algorithm of Moser & Tardos (2010) provided an efficient randomized algorithm to implement it. This algorithm could be parallelized to give an algorithm that uses polynomially many processors and $O(\log^3 n)$ time, stemming from $O(\log n)$ adaptive computations of a maximal independent set (MIS). Chung et. al. (2014) developed faster local and parallel algorithms, potentially running in time $O(\log^2 n)$, but these algorithms work under significantly more stringent conditions than the LLL. We give a new parallel algorithm, that works under essentially the same conditions as the original algorithm of Moser & Tardos, but uses only a single MIS computation, thus running in $O(\log^2 n)$ time. This conceptually new algorithm also gives a clean combinatorial description of a satisfying assignment which might be of independent interest. Our techniques extend to the deterministic LLL algorithm given by Chandrasekaran et al (2013) leading to an NC-algorithm running in time $O(\log^2 n)$ as well. We also provide improved bounds on the run-times of the sequential and parallel resampling-based algorithms originally developed by Moser & Tardos. These bounds extend to any problem instance in which the tighter Shearer LLL criterion is satisfied. We also improve on the analysis of Kolipaka & Szegedy (2011) to give tighter concentration results. Interestingly...

## Parallel Algorithms for Counting Triangles in Networks with Large Degrees

Arifuzzaman, Shaikh; Khan, Maleq; Marathe, Madhav
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.24%
Finding the number of triangles in a network is an important problem in the analysis of complex networks. The number of triangles also has important applications in data mining. Existing distributed memory parallel algorithms for counting triangles are either Map-Reduce based or message passing interface (MPI) based and work with overlapping partitions of the given network. These algorithms are designed for very sparse networks and do not work well when the degrees of the nodes are relatively larger. For networks with larger degrees, Map-Reduce based algorithm generates prohibitively large intermediate data, and in MPI based algorithms with overlapping partitions, each partition can grow as large as the original network, wiping out the benefit of partitioning the network. In this paper, we present two efficient MPI-based parallel algorithms for counting triangles in massive networks with large degrees. The first algorithm is a space-efficient algorithm for networks that do not fit in the main memory of a single compute node. This algorithm divides the network into non-overlapping partitions. The second algorithm is for the case where the main memory of each node is large enough to contain the entire network. We observe that for such a case...

## Parallel algorithms in linear algebra

Brent, Richard P.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.21%
This report provides an introduction to algorithms for fundamental linear algebra problems on various parallel computer architectures, with the emphasis on distributed-memory MIMD machines. To illustrate the basic concepts and key issues, we consider the problem of parallel solution of a nonsingular linear system by Gaussian elimination with partial pivoting. This problem has come to be regarded as a benchmark for the performance of parallel machines. We consider its appropriateness as a benchmark, its communication requirements, and schemes for data distribution to facilitate communication and load balancing. In addition, we describe some parallel algorithms for orthogonal (QR) factorization and the singular value decomposition (SVD).; Comment: 17 pages. An old Technical Report, submitted for archival purposes. For further details see http://wwwmaths.anu.edu.au/~brent/pub/pub128.html

## Distributed and Parallel Algorithms for Set Cover Problems with Small Neighborhood Covers

Agarwal, Archita; Chakaravarthy, Venkatesan T.; Choudhury, Anamitra R.; Roy, Sambuddha; Sabharwal, Yogish
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.18%
In this paper, we study a class of set cover problems that satisfy a special property which we call the {\em small neighborhood cover} property. This class encompasses several well-studied problems including vertex cover, interval cover, bag interval cover and tree cover. We design unified distributed and parallel algorithms that can handle any set cover problem falling under the above framework and yield constant factor approximations. These algorithms run in polylogarithmic communication rounds in the distributed setting and are in NC, in the parallel setting.; Comment: Full version of FSTTCS'13 paper

## Design and implementation of self-adaptable parallel algorithms for scientific computing on highly heterogeneous HPC platforms

Lastovetsky, Alexey; Reddy, Ravi; Rychkov, Vladimir; Clarke, David
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.3%
Traditional heterogeneous parallel algorithms, designed for heterogeneous clusters of workstations, are based on the assumption that the absolute speed of the processors does not depend on the size of the computational task. This assumption proved inaccurate for modern and perspective highly heterogeneous HPC platforms. New class of algorithms based on the functional performance model (FPM), representing the speed of the processor by a function of problem size, has been recently proposed. These algorithms cannot be however employed in self-adaptable applications because of very high cost of construction of the functional performance model. The paper presents a new class of parallel algorithms for highly heterogeneous HPC platforms. Like traditional FPM-based algorithms, these algorithms assume that the speed of the processors is characterized by speed functions rather than speed constants. Unlike the traditional algorithms, they do not assume the speed functions to be given. Instead, they estimate the speed functions of the processors for different problem sizes during their execution. These algorithms do not construct the full speed function for each processor but rather build and use their partial estimates sufficient for optimal distribution of computations with a given accuracy. The low execution cost of distribution of computations between heterogeneous processors in these algorithms make them suitable for employment in self-adaptable applications. Experiments with parallel matrix multiplication applications based on this approach are performed on local and global heterogeneous computational clusters. The results show that the execution time of optimal matrix distribution between processors is significantly less...

## Improved Parallel Algorithms for Spanners and Hopsets

Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.21%
We use exponential start time clustering to design faster and more work-efficient parallel graph algorithms involving distances. Previous algorithms usually rely on graph decomposition routines with strict restrictions on the diameters of the decomposed pieces. We weaken these bounds in favor of stronger local probabilistic guarantees. This allows more direct analyses of the overall process, giving: * Linear work parallel algorithms that construct spanners with $O(k)$ stretch and size $O(n^{1+1/k})$ in unweighted graphs, and size $O(n^{1+1/k} \log k)$ in weighted graphs. * Hopsets that lead to the first parallel algorithm for approximating shortest paths in undirected graphs with $O(m\;\mathrm{polylog}\;n)$ work.

## Practical Parallel External Memory Algorithms via Simulation of Parallel Algorithms

Robillard, David E.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.33%
This thesis introduces PEMS2, an improvement to PEMS (Parallel External Memory System). PEMS executes Bulk-Synchronous Parallel (BSP) algorithms in an External Memory (EM) context, enabling computation with very large data sets which exceed the size of main memory. Many parallel algorithms have been designed and implemented for Bulk-Synchronous Parallel models of computation. Such algorithms generally assume that the entire data set is stored in main memory at once. PEMS overcomes this limitation without requiring any modification to the algorithm by using disk space as memory for additional "virtual processors". Previous work has shown this to be a promising approach which scales well as computational resources (i.e. processors and disks) are added. However, the technique incurs significant overhead when compared with purpose-built EM algorithms. PEMS2 introduces refinements to the simulation process intended to reduce this overhead as well as the amount of disk space required to run the simulation. New functionality is also introduced, including asynchronous I/O and support for multi-core processors. Experimental results show that these changes significantly improve the runtime of the simulation. PEMS2 narrows the performance gap between simulated BSP algorithms and their hand-crafted EM counterparts...

## Computing Multidimensional Aggregates in Parallel

Liang, Weifa; Orlowska, Maria
Fonte: Slovene Society Informatika Publicador: Slovene Society Informatika
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.26%
Computing multiple related group-bys and aggregates is one of the core operations of On-Line Analytical Processing (OLAP) applications. This kind of computation involves a huge volume of data operations (megabytes or treabytes). The response time for such applications is crucial, so, using parallel processing techniques to handle such computation is inevitable. In this paper we present several parallel algorithms for computing a collection of group-by aggregations based on a multiprocessor system with sharing disks. We focus on a special case of the aggregation problem-'Cube' operator which computes group-by aggregations over all possible combinations of a list of attributes. The proposed algorithms introduce a novel processor scheduling policy and a non-trivial decomposition approach for the problem in the parallel environment. Particularly, we believe the proposed hybrid algorithm has the best performance potential among the four proposed algorithms. All the proposed algorithms are scalable.

## Scalable parallel algorithms for surface fitting and data mining

Christen, Peter; Hegland, Markus; Nielsen, Ole; Roberts, Stephen; Strazdins, Peter; Altas, I