Lancer de rayon : approches parallèles

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Schemas d'execution pour les machines paralleles a memoire distribuee. Une etude de cas: le lancer de rayon

SIGLEINIST T 76434 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

VM_pRAY an efficient ray tracing algorithm on a distributed memory parallel computer

The production of realistic image generated by computer requires a huge amount of computation and a large memory capacity. The use of highly parallel machines allows this process to be performed faster. Distributed memory parallel computers (DMPCs), such as hypercubes or transputer-based machines, offer an interesting performance/cost ratio when assuming that a load balancing and a partition of the data domain have been performed. This paper presents a software running on an iPSC/2 whose name is VM-pRAY. The aim of this experimental software is to show that using a virtual shared memory is an efficient strategy for parallelizing algorithms which, like ray tracing, use large read-only databases with no obvious data domain decomposition. The source code of VM-pRAY for an hypercube iPSC/2 is given in the appendix

Opérations booléennes sur polyèdres : évaluation d'arbres CGS

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Ray tracing on distributed memory parallel computers : strategies for distributing computations and data

The ray tracing algorithm produces high quality images, but it requires a lot of computations which makes it extremely time-consuming. Several attempts have been made to reduce the synthesis time by using high speed parallel computers. For example, distributed memory parallel computers, such as hypercubes or transputer-based machines, offer an interesting performance/cost ratio. Several studies have used parallel computers to speed up the ray tracing algorithm so as to render complex scenes with several thousands of objects. However few of them have led to real implementation due to the complexity of the solution proposed by the authors. This paper introduces a new approach emulating a read-only shared memory on a distributed memory parallel computer. Results are given and are compared to a previous parallel ray tracing algorithm, both are implemented on an iPSC/2

Lancer de rayon : approches parallèles

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SVMview: a Performance Tuning Tool for DSM-based Parallel Computers

This paper describes a performance tuning tool, named SVMview, for DSM-based parallel computers. SVMview is a tool for doing a post-mortem analysis of page movements generated during the execution of Fortran-S programs. This tool is able to analyze some particular phenomena such as false-sharing which occurs when several processors write to the same page simultaneously. Such behavior entails badly the performance of DSM systems, and thus are particularly important to be detected

KOAN : a versatile tool for parallelizing realistic rendering algorithms

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Routing Strategies and Message Contention on Low-dimensional Interconnection Networks

Non-uniform message distribution in interconnection networks is a common problem and causes network congestion. This paper proves that a careful choice of the routing algorithm can increase significantly the communication performance under pathological communication patterns, such as hot spots. A comparison between widely used e-cube routing and a new algorithm based on Computer Graphics line drawing techniques has been made for k-ary n-cube networks. The algorithm proposed uniformly distributes the direction in the path followed by the messages, thus loading in a more uniform way the links in the direction of the hot spot. The problem is analyzed both theoretically, and through simulations. Index Terms Routing algorithms, interconnection networks, hot spots contention, highly parallel systems. 1 Introduction Distributed memory parallel computers have gained wide acceptance as a cost-effective approach to large-scale computers. One of their major advantages lies in the fact that the ..