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Title

Computational advances in gravitational microlensing: a comparison of CPU, GPU, and parallel, large data codes

Author(s)

Bate, N. F.;  Fluke, C. J.;  Barsdell, B. R.;  Garsden, H.;  Lewis, G. F.

Abstract

To assess how future progress in gravitational microlensing computation at high optical depth will rely on both hardware and software solutions, we compare a direct inverse ray-shooting code implemented on a graphics processing unit (GPU) with both a widely-used hierarchical tree code on a single-core CPU, and a recent implementation of a parallel tree code suitable for a CPU-based cluster supercomputer. We examine the accuracy of the tree codes through comparison with a direct code over a much wider range of parameter space than has been feasible before. We demonstrate that all three codes present comparable accuracy, and choice of approach depends on considerations relating to the scale and nature of the microlensing problem under investigation. On current hardware, there is little difference in the processing speed of the single-core CPU tree code and the GPU direct code, however the recent plateau in single-core CPU speeds means the existing tree code is no longer able to take advantage of Moore's law-like increases in processing speed. Instead, we anticipate a rapid increase in GPU capabilities in the next few years, which is advantageous to the direct code. We suggest that progress in other areas of astrophysical computation may benefit from a transition to GPUs through the use of " brute force" algorithms, rather than attempting to port the current best solution directly to a GPU language - for certain classes of problems, the simple implementation on GPUs may already be no worse than an optimised single-core CPU version.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

New Astronomy, Vol. 15, no. 8 (Nov 2010), pp. 726-734

Publication year

2010

FOR Code(s)

0201 Astronomical and Space Sciences

Keyword(s)

Gravitational lensing;  Numerical methods

Publisher

Elsevier BV

ISSN

1384-1076

Publisher URL

http://dx.doi.org/10.1016/j.newast.2010.05.008

Copyright

Copyright © 2010 Elsevier B.V. The accepted manuscript is reproduced in accordance with the copyright policy of the publisher.

Full text

Peer reviewed