Accelerating octo-tiger: Stellar mergers on intel knights landing with HPX

Document Type

Conference Proceeding

Publication Date

5-14-2018

Abstract

The optimization of performance of complex simulation codes with high computational demands, such as Octo-Tiger, is an ongoing challenge. Octo-Tiger is an astrophysics code simulating the evolution of star systems based on the fast multipole method using adaptive octrees as the central data structure. Octo-Tiger was implemented using high-level C++ libraries, specifically HPX and Vc, which allows its use on different hardware platforms. Recently, we have demonstrated excellent scalability in a distributed setting. In this paper, we study the node-level performance of Octo-Tiger on an Intel Knights Landing platform. We focus on Octo-Tiger's fast multipole method, as it is the computationally most demanding component. By using HPX and a futurization approach, we can efficiently traverse the adaptive octrees in parallel. On the core-level, threads process sub-grids using multiple 1074-element stencils. In numerical experiments, simulating the time evolution of a rotating star on an Intel Xeon Phi 7250 Knights Landing processor, Octo-Tiger shows good parallel efficiency. For the fast multipole algorithm, we achieved up to 408 GFLOPS, resulting in a speedup of 2x compared to a 24-core Skylake-SP platform, using the same high-level abstractions.

Publication Source (Journal or Book title)

ACM International Conference Proceeding Series

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