Experiments in running a scientific MPI application on Grid´5000

Over the last couple of years, several dedicated grid platforms have been set up to test applications and middleware for grids. Among these is Grid´5000, a reconfigurable platform gathering resources at nine remote geographical sites in France. This paper presents one of the eight experiments that have tested software scalability at the scale of a thousand processors (i.e. 500-1000) on this grid testbed. The experiment aims at analyzing the behavior of a geophysical application (a seismic ray tracing in a 3D mesh of the Earth). The application is computationally intensive but requires an all-to-all communication phase during which processors exchange their results, which has shown to be a real bottleneck on many hardware platforms. We analyze various runs and show that this application scales well up to about 500 processors on such a grid.