Performance of particle in cell methods on highly concurrent computational architectures | |
M.F.Adams ; S. Ethier ; N. Wichmann | |
关键词: COMPUTER CALCULATIONS; MEMORY MANAGEMENT; BOLTZMANN-VLASOV EQUATION; POISSON EQUATION; PERFORMANCE; ITER TOKAMAK; PLASMA PIC; gyrokinetic; | |
DOI : 10.2172/963137 RP-ID : DOE/FG/25715 PID : OSTI ID: 963137 Others : TRN: US1000169 |
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美国|英语 | |
来源: SciTech Connect | |
【 摘 要 】
Particle in cell (PIC) methods are effective in computing Vlasov-Poisson system of equations used in simulations of magnetic fusion plasmas. PIC methods use grid based computations, for solving Poissonâs equation or more generally Maxwellâs equations, as well as Monte-Carlo type methods to sample the Vlasov equation. The presence of two types of discretizations, deterministic field solves and Monte-Carlo methods for the Vlasov equation, pose challenges in understanding and optimizing performance on today large scale computers which require high levels of concurrency. These challenges arises from the need to optimize two very different types of processes and the interactions between them. Modern cache based high-end computers have very deep memory hierarchies and high degrees of concurrency which must be utilized effectively to achieve good performance. The effective use of these machines requires maximizing concurrency by eliminating serial or redundant work and minimizing global communication. A related issue is minimizing the memory traffic between levels of the memory hierarchy because performance is often limited by the bandwidths and latencies of the memory system. This paper discusses some of the performance issues, particularly in regard to parallelism, of PIC methods. The gyrokinetic toroidal code (GTC) is used for these studies and a new radial grid decomposition is presented and evaluated. Scaling of the code is demonstrated on ITER sized plasmas with up to 16K Cray XT3/4 cores.
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RO201705170000911LZ | 2665KB | download |