Provably optimal parallel transport sweeps on regular grids

Conference · Mon Jul 01 04:00:00 EDT 2013

OSTI ID:22212896

Adams, M. P.; Adams, M. L.; Hawkins, W. D. ^[1]; Smith, T.; Rauchwerger, L.; Amato, N. M. ^[2]; Bailey, T. S.; Falgout, R. D. ^[3]

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1. Dept. of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77843-3133 (United States)
2. Dept. of Computer Science and Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77843-3133 (United States)
3. Lawrence Livermore National Laboratory (United States)

We have found provably optimal algorithms for full-domain discrete-ordinate transport sweeps on regular grids in 3D Cartesian geometry. We describe these algorithms and sketch a 'proof that they always execute the full eight-octant sweep in the minimum possible number of stages for a given P{sub x} x P{sub y} x P{sub z} partitioning. Computational results demonstrate that our optimal scheduling algorithms execute sweeps in the minimum possible stage count. Observed parallel efficiencies agree well with our performance model. An older version of our PDT transport code achieves almost 80% parallel efficiency on 131,072 cores, on a weak-scaling problem with only one energy group, 80 directions, and 4096 cells/core. A newer version is less efficient at present-we are still improving its implementation - but achieves almost 60% parallel efficiency on 393,216 cores. These results conclusively demonstrate that sweeps can perform with high efficiency on core counts approaching 10{sup 6}. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 22212896
• Country of Publication: United States
• Language: English

Related Subjects

97 MATHEMATICS AND COMPUTING
ALGORITHMS
DISCRETE ORDINATE METHOD
EFFICIENCY
OPTIMIZATION
PARTITION
PERFORMANCE
SCALING