Performance analysis of direct N-body algorithms on special-purpose supercomputers

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 i...

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Bibliographic Details
Published in:New astronomy 2007-07, Vol.12 (5), p.357-377
Main Authors: Harfst, Stefan, Gualandris, Alessia, Merritt, David, Spurzem, Rainer, Zwart, Simon Portegies, Berczik, Peter
Format: Article
Language:English
Subjects:
Methods: N-Body simulations
Stellar dynamics
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Summary: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 60% and speeds in excess of ∼3 TFlops are reached.
ISSN:1384-1076
1384-1092
DOI:10.1016/j.newast.2006.11.003