Performance Analysis of an Embarrassingly Parallel Application in Atmospheric Modeling

摘要

This study aims at making a comparative study of various parallel programming models for a compute intensive application pertaining to Atmospheric modeling. Atmospheric modeling deals with predicting the behavior of atmosphere through mathematical equations governing the atmospheric fluid flows. The mathematical equations are nonlinear partial differential equations which are difficult to solve analytically. Thus fundamental governing equations of atmospheric motion are discretized into algebraic forms that are solved using numerical methods to obtain flow-field values at discrete points in time and/or space. Solving these equations often requires huge computational resource, which is normally available with high-speed supercomputers. Shallow Water equations provide a useful framework for the analysis of dynamics of large-scale atmospheric flow and for the analysis of various numerical methods that might be applied to the solution of these equations. In this study, Finite volume approach has been used for discretizing these equations that leads to a number of algebraic equations equal to the number of time instants at which the flow field values are to be evaluated. It is apparent that the application is embarrassingly parallel and its parallelization will suppress communication overhead. A High Performance Compute cluster has been employed for solving the equations involved in atmospheric modeling. Use of OpenMP and MPI APIs has paved the way to study the behavior of shared memory programming model and the message passing programming model in the context of such a highly compute intensive application. It is observed that no additional benefit can be enjoyed by creating too many software threads than the available hardware threads, as the execution resources should be shared among them.