Um processo Otimizado de produção de mapas da radiação cósmica de fundo em microondas / An optimized process of production of cosmic microwave backgroud radiation maps

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

27/03/2003

RESUMO

The current work describes the optimization and parallelization of the software for the production of Cosmic Microwave Background (CMB) radiation maps in a distributed memory architecture. Initially, the Fortran code was ported to Fortran 90 and to High Performance Fortran (HPF) and run in a SMP (Shared Memory Processor) machine. In order to provide timing information, calls to operating system timing routines were imbedded in the code. Analysis of timing information shows performance bottlenecks in the matrix convolution routine, which is done by a two-dimensional Fast Fourier Transform (FFT) algorithm. This is a time consuming routine due to data distribution among processors. Due to the FFT algorithm the convolution matrix has to be transposed. Typically, a block of columns of this matrix is assigned to each processor but, in order to calculate the transposed matrix, block of lines of the same matrix must be read. This was clearly an inefficient issue running HPF on that machine. The FFT routine was ported to Message Passing Interface (MPI) mixing task and data parallelism. The used distributed memory machine is a Beowulf cluster, each node being a Linux IA-32 computer. The use of MPI to enhance HPF performance was already proposed by Foster et al. in ?Double standards: bringing task parallelism to HPF via the Message Passing Interface? and was used in the 2D FFT routine in order to provide a more efficient communication between nodes in the calculation of the transposed matrix. This work presents the evaluations of the used method, and the same approach could be used in other time consuming routines of the CMB code. The timing analysis provides clues to enhance load balancing and data communication between nodes.

ASSUNTO(S)

radiação cósmica de fundo em microondas (rcfm) sistemas de processamento paralelo redução de dados fortran (linguagem de programação) programação de sistemas computacionais

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