%0 Journal Article
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%3 performance analysis.pdf
%X Three algorithms for solving the radiative transfer equation (RTE) were studied: Hydrolight, PEESNA and LTSN. These algorithms correspond, respectively, to invariant imbedding, analytical discrete-ordinates and LTSN methods. As a first step, the performance of each algorithm was evaluated running in the same sequential machine. The related codes were used in a Hydrological Optics typical coastal water test case, in order to calculate the surface-emergent radiation intensities (radiances) given the incident radiances and inherent optical properties such as the absorption and the scattering coefficients. Timing and profiling of the three codes was performed in order to evaluate processing times and to identify performance bottlenecks. Next, each algorithm was studied concerning the feasibility of its parallelization using the MPI message passing communication library and execution in a distributed memory machine, a multicomputer based on IA-32 architecture. The three codes perform spatial discretization of the domain and Fourier decomposition of the radiances obtaining independent azimuthal modes. Therefore, an independent RTE can be written for each azimuthal mode and can be assigned to a different processor, in a parallel implementation. The speed-up that can be achieved increases with the fraction of time spent in the azimuthal mode, but total execution time is also an important issue. Results are discussed and further strategies are proposed.
%N 5-7
%T Performance analysis of radiative transfer algorithms in a parallel environment
%@secondarytype PRE PI
%K COMPUTER SCIENCE, Algorithms, Radiative transfer equation (RTE), Hydrolight, PEESNA, LTSN, Hydrological optics, COMPUTAÇÃO APLICADA, Algorítmos, Equação de transferência radioativa, Ótica hidrológica.
%@visibility shown
%@group LAC-INPE-MCT-BR
%@group LAC-INPE-MCT-BR
%@group LAC-INPE-MCT-BR
%@group LAC-INPE-MCT-BR
%@secondarykey INPE-12877-PRE/8167
%@copyholder SID/SCD
%@issn 0041-1450
%2 sid.inpe.br/marciana/2005/07.11.12.53.53
%@affiliation Instituto Nacional de Pesquisas Espaciais, Laboratório Associado de Computação e Matemática  Aplicada, (INPE. LAC)
%@affiliation Instituto Nacional de Pesquisas Espaciais, Laboratório Associado de Computação e Matemática  Aplicada, (INPE. LAC)
%@affiliation Instituto Nacional de Pesquisas Espaciais, Laboratório Associado de Computação e Matemática  Aplicada, (INPE. LAC)
%@affiliation Instituto Nacional de Pesquisas Espaciais, Laboratório Associado de Computação e Matemática  Aplicada, (INPE. LAC)
%@project Processamento de alto desempenho
%B Transport Theory and Statistical Physics
%P 449-468
%4 sid.inpe.br/marciana/2005/07.11.12.53
%D 2004
%V 33
%A Souto, Roberto Pinto,
%A Campos Velho, Haroldo Fraga de,
%A Stephany, Stephan,
%A Chalhoub, Ezzat Selim,
%@dissemination WEBSCI
%@area COMP