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Implementation of a Message Passing Interface into a Cloud-Resolving Model for Massively Parallel ComputingThe capability for massively parallel programming (MPP) using a message passing interface (MPI) has been implemented into a three-dimensional version of the Goddard Cumulus Ensemble (GCE) model. The design for the MPP with MPI uses the concept of maintaining similar code structure between the whole domain as well as the portions after decomposition. Hence the model follows the same integration for single and multiple tasks (CPUs). Also, it provides for minimal changes to the original code, so it is easily modified and/or managed by the model developers and users who have little knowledge of MPP. The entire model domain could be sliced into one- or two-dimensional decomposition with a halo regime, which is overlaid on partial domains. The halo regime requires that no data be fetched across tasks during the computational stage, but it must be updated before the next computational stage through data exchange via MPI. For reproducible purposes, transposing data among tasks is required for spectral transform (Fast Fourier Transform, FFT), which is used in the anelastic version of the model for solving the pressure equation. The performance of the MPI-implemented codes (i.e., the compressible and anelastic versions) was tested on three different computing platforms. The major results are: 1) both versions have speedups of about 99% up to 256 tasks but not for 512 tasks; 2) the anelastic version has better speedup and efficiency because it requires more computations than that of the compressible version; 3) equal or approximately-equal numbers of slices between the x- and y- directions provide the fastest integration due to fewer data exchanges; and 4) one-dimensional slices in the x-direction result in the slowest integration due to the need for more memory relocation for computation.
Document ID
20040171260
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Juang, Hann-Ming Henry (National Centers for Environmental Prediction Washington, DC, United States)
Tao, Wei-Kuo (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Zeng, Xi-Ping (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Shie, Chung-Lin (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Simpson, Joanne (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lang, Steve (Science Systems and Applications, Inc. Lanham, MD, United States)
Date Acquired
September 7, 2013
Publication Date
June 2, 2004
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Public Use Permitted.

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