Advanced Scientific Computing
Electrodynamics on QCDOC and BG/L
R. Bennett and N. D'Imperio
We studied the performance of our electrodynamics code MAXSSIM (see
4.4.5) on several massively parallel machines. MAXSSIM is a parallel,
scalable, finite-difference time-domain code, which solves Maxwell’s
equations using the Yee algorithm [1].
It is possible to choose parameters such that communication among
processors is a small fraction of the computation time. Thus it provides
an important initial test bed for massively parallel machines.
We have ported the code to QCDOC, BlueGene/L, and to the Compaq
Alphaserver at the Pittsburgh Supercomputer Center (PSC). We chose a
modest sized problem on a 72x72x2048 mesh and evaluated the performance
on up to 1024 processors.
Figure 1 shows the actual number of floating point operations (sustained
performance) as a function of the number of processors on the three
machines. Scaling is quite good in all cases (this is a fixed problem
size, so this is an example of strong scaling), although the percentage
of peak performance achieved on 1024 processors is relatively low –
approximately 33.8% on the PSC machine, 22.5% on BG/L and 9.1% on QCDOC.
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Figure 1. |
References
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[1] Yee, K.S. Numerical solution of initial boundary value problems in
isotropic media. IEEE Trans. Antennas and Propagation 14: 302 (1996).
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[2] Bennett, R. and D’Imperio, N.L. Performance evaluation of a 3D
electrodynamics simulation on massively parallel computers. SIAM
Parallel Processing, 2006.
Last Modified: April 23, 2009
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Claire Lamberti
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