Direct-summation N-body algorithms compute the gravitational interaction between stars in an exact way and have a computational complexity of O(N^2). Performance can be greatly enhanced via the use of special-purpose accelerator boards like the GRAPE-6A. However the memory of the GRAPE boards is limited. Here, we present a performance analysis of direct N-body codes on two parallel supercomputers that incorporate special-purpose boards, allowing as many as four million particles to be integrated. Both computers employ high-speed, Infiniband interconnects to minimize communication overhead, which can otherwise become significant due to the small number of "active" particles at each time step. We find that the computation time scales well with processor number; for 2*10^6 particles, efficiencies greater than 50% and speeds in excess of 2 TFlops are reached

Publication Date



This is the pre-print of an article published by Elsevier. Copyright 2007 Elsevier B.V. The final, published version is located here: https://doi.org/10.1016/j.newast.2006.11.003

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Document Type


Department, Program, or Center

Center for Advancing the Study of CyberInfrastructure


RIT – Main Campus