Proceedings of the Fifth Distributed Memory Computing Conference, 1990.最新文献

{"title":"Massively Parallel Computation of the Euler Equations","authors":"C. Grosch, M. Ghose, S.N. Gupta, T. L. Jackson, M. Zubair","doi":"10.1109/DMCC.1990.555419","DOIUrl":"https://doi.org/10.1109/DMCC.1990.555419","url":null,"abstract":"We present a systematic study of the applicability of massively parallel computers, the AMT DAP-510/610 and the TMC CM-2, to the solution of the two-dimensional unsteady Euler equa tions using a compact high-order scheme. The performance of these machines is compared to that of the Cray-2 and the Cray-YMP/832 using the same algorithm and for the same test problem.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115264077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Communication Parameter Tests and Parallel Back Propagation Algorithms on iPSC/2 Hypercube Multiprocessor","authors":"B. Mak, O. Egecioglu","doi":"10.1109/DMCC.1990.556397","DOIUrl":"https://doi.org/10.1109/DMCC.1990.556397","url":null,"abstract":"The communication complexity on Intel’s second generation iPSC/2 hypercube and its effect on parallelization of Back Propagation type training algorithms for neural networks are explored. On iPSC/2 , different broadcasting methods are tested and three inter-node communication schemes are evaluated based on their performance on vector addition. These communication schemes are then utilized on parallel versions of the Back Propagation training algorithm. The performance of the resulting parallel variants of Back Propagation are analyzed using two medium size problems: vowel classification and English text-to-speech conversion (NETtalk data).","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123338190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of Dual Ported Memories from the Task Level","authors":"Rutger F. H. Hofman","doi":"10.1109/DMCC.1990.556267","DOIUrl":"https://doi.org/10.1109/DMCC.1990.556267","url":null,"abstract":"An architecture, which is a hybrid of local memory and shared memory, is described in this report: it uses dual ported memories (DPMs), each accessed by two processors. Each processor is connected to a number of DPMs. The profit that is gained by using a DPM as a shared memory between two processors appears from task allocation results: task transport costs are avoided when a task, newly created in DPM d by one of d’s two processors, is allocated to the other processor at d. For a number of task allocation strategies, simulation studies show that the fraction of the tasks that benefit from this optimisation decreases with the number of processors in the multiprocessor. For larger numbers of processors, this fraction is considerably higher than the fraction under random allocation.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125575999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular Dynamics Simulations of Short-Range Force Systems on 1024-Node Hypercubes","authors":"S. Plimpton","doi":"10.1109/DMCC.1990.555423","DOIUrl":"https://doi.org/10.1109/DMCC.1990.555423","url":null,"abstract":"Two parallel algorithms for classical molecular dynamics are presented. The first assigns each processor to a subset of particles; the second assigns each to a fixed region of 3d space. The algorithms are implemented on 1024-node hypercubes for problems characterized by short-range forces, diffusion (so that each particle’s neighbors change in time), and problem size ranging from 250 to 10000 particles. Timings for the algorithms on the 1024-node NCUBE/ten and the newer NCUBE 2 hypercubes are given. The latter is found to be competitive with a CRAY-XMP, running an optimized serial algorithm. For smaller problems the NCUBE 2 and CRAY-XMP are roughly the same; for larger ones the NCUBE 2 (with 1024 nodes) is up to twice as fast. Parallel efficiencies of the algorithms and communication parameters for the two hypercubes are also examined.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130773478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypercube Dynamic Load Balancing","authors":"D. King, E. Wegman","doi":"10.1109/DMCC.1990.556305","DOIUrl":"https://doi.org/10.1109/DMCC.1990.556305","url":null,"abstract":"This paper reports on the results of a preliminary study in dynamic load balancing on an Intel Hypercube. The purpose of this research is to provide experimental data in how parallel algorithms should be constructed to obtain maximal utilization of a parallel architecture. This study is one aspect of an ongoing research project into the construction of an automated parallelization tool. This tool will take FORTRAN source as input, and construct a parallel algorithm that will produce the same results as the original serial input. The focus of this paper is on the load balancing aspect of that project. The basic idea is to reserve a certain percentage of the computation task, subdivide that percentage into arbitrarily fine tasks, and dole those small tasks out to nodes on request. Ij” the percentage is chosen correctly, then a minority of nodes should be involved in consuming the filler tasks, and the overall throughput of the job should increase as a result of the individual node efJciencies having increased. This paper will outline our approach to performing dynamic load balancing on an Intel iPSC/2. We take the view that the problem of load balancing is really a problem of dividing a “computational task” into smaller components, each of roughly equal complexity, and each an independent event. After this is done, the components of the task can be sent to a node for execution. The key to an optimally balanced load across all computational nodes is the ability to form a statistical profile of the individual components of each computational task. This statistical profile will determine an initial sequence of execution. Our experience indicates that a speedup on the order of 80% is achievable with the judicious use of profiled load balancing. During the process of execution, the initial profile will be altered according to the actual behavior exhibited by the nodes. The difference between the actual and expected performance will be used to determine how much additional time should be devoted to altering the current execution schedule. Currently, our work involves statically setting the load balancing parameters. Our load balancing system determines the execution schedule","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128696924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface Reconstruction and Discontinuity Detection: A Fast Hierarchical Approach on a Two-Dimensional Mesh","authors":"R. Battiti","doi":"10.1109/DMCC.1990.555382","DOIUrl":"https://doi.org/10.1109/DMCC.1990.555382","url":null,"abstract":"Recently multigrid techniques have been proposed for solving low-level vision problems in optimal time (i.e. time proportional to the number of pixels). In the present work this method is extended to incorporate a discontinuity detection process cooperating with the smoothing phase on all scales. Activation of line element detectors that signal the presence of relevant discontinuities is based on information gathered from neighboring points at the same and different scales. Because the required computation is local, parallelism can be profitably used. A mapping of the required data structure onto a two dimensional mesh of processors is suggested. Domain decomposition is shown to be efficient on MIMD computers capable of containing many individual cells in each processor. Some examples of the proposed multiscale solution techniques are shown for two different applications. In the first case a surface is reconstructed from first derivative information (extracted from the intensity data), in the second case from noisy depth constraints.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121840684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parallel Loops on Distributed Machines","authors":"C. Koelbel, P. Mehrotra, J. Saltz, H. Berryman","doi":"10.1109/DMCC.1990.556322","DOIUrl":"https://doi.org/10.1109/DMCC.1990.556322","url":null,"abstract":"Any programming environment for distributed memory machines that allows the user to specify pdwallel do loops over globally defined data structures requires optimizations that go beyond the specification of Lrppropriate data and workload partitionings. In this paper, we consider optimizations that are required for efficient execution of a code segment that consists of pmallel loops over distributed data Structures. On distributed memory machines it is typically very expensive tci fetch individual data elements. Instead, before a parallirl loop executes, it is desirable to prefetch all off-processor data required in the loop. We specify a scheme for s boring copies of fetched data along with a scheme for accessing copies of off-processor data during the computafJ ion of the loop. The performance of such optimizations rm the iPSC/2 and the NCUBE is also presented.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116018461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Parallel Distributed-Memory Implementation of the Corrective Switching Problem","authors":"J. Blanc, D. Trystram, J. Ryckbosch","doi":"10.1109/DMCC.1990.555358","DOIUrl":"https://doi.org/10.1109/DMCC.1990.555358","url":null,"abstract":"LMC-IIVLAG EDF-DER Abstract. For the past 20 years, an increasing interest has been devoted to the sequential Conjugate Gradient Method for solving large linear systems arising from the modeling of physical problems (especially for very large systems with sparse matrices). This paper deals with the implementation on parallel supercomputers of a preconditioned conjugate gradient method for solving the corrective switching problem obtained while modeling the behavior of power systems in electrical networks. This problem consists in finding the successive solutions of many close linear systems (not too large) with very ill-conditioned matrices (sometimes even singular). We present a new method based on the Preconditioned Conjugate Gradient algorithm with an original preconditioning and study its parallelization on both shared and distributed memory computers. 1. Setting of the problem During the control of electrical networks, the operator must ensure the system to bc in a safc state (i.e. to be able to protect the system against incidents liable to occur in real time). The demand and the possibility of the plants are such that nuclear energy between two plants flows from various nodes of the network. The loss of one element could jeopardize the security of the whole system by a chain tripping: in such case, an overload line occurs and without any operation the protective devices will act and the line will trip out. In actual operations conditions, the switching actions that the operator applies to the electrical network ensure that overloads will disappear before the delayed protective devices go into action. Such actions are shown on the picture at the end of the paper. The computation of switching actions is a combinatorial problem, very hard to solve. The connections of the switching elements are described as discrete variables. The corrective switching problem corresponds to determine the various possible solutions of the load flow calculation. Each such situation requires to solve a linear system where the matrices have only a few elements which differ from each other. Let us consider the N consecutive linear systems below: (Si) Ajx; = b;, lG<N where the matrices Ai (of size n by n) are \"close\" to each other, viz, A;+1 = Ai+Ai, with Ai of small norm. The solutions xi will be close to each other in this sense, and we want to take full advantage of this. Note that this problem also occurs in Adaptive Filtering or Finite Element modeling.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"158 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116306272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Adaptive Multiscale Scheme for Real-Time Motion Field Estimation","authors":"R. Battiti","doi":"10.1109/DMCC.1990.555383","DOIUrl":"https://doi.org/10.1109/DMCC.1990.555383","url":null,"abstract":"The problem considered in this work is that of estimating the motion field (i.e. the projection of the velocity field onto the image plane) from a temporal sequence of images. Generic images contain different objects with diverse spatial frequencies and motion amplitudes. To deal with this complex environment in a fast and effective way, biological visual systems use parallel processing, visual channels at different resolutions and adaptive mechanisms. In this paper a new adaptive multiscale scheme is proposed, in which the spatial discretization scale is based on a local estimate of the errors involved. Considering the constraints for real-time operation, flexibility and portability, the scheme can be implemented on MIMD parallel computers with medium size grains with high efficiency. Tests with ray-traced and video-acquired images for different motion ranges show that this method produces a better estimation with respect to the homogeneous (no Gadap t ive) mult iscale met hod.","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126646154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hot-Spot Performance of Single-Stage and Multistage Interconnection Networks","authors":"K. Gunter, E. Gehringer","doi":"10.1109/DMCC.1990.556269","DOIUrl":"https://doi.org/10.1109/DMCC.1990.556269","url":null,"abstract":"","PeriodicalId":204431,"journal":{"name":"Proceedings of the Fifth Distributed Memory Computing Conference, 1990.","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126673213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}