PANGFENG LIUBhatt, Sandeep N.Sandeep N.Bhatt2020-05-042020-05-041994https://scholars.lib.ntu.edu.tw/handle/123456789/489388https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947725835&doi=10.1145%2f181014.181081&partnerID=40&md5=1578cc4275dcda83c765b13b57ab0c44This paper describes our experiences developing high- performance code for astrophysical iV-body simulations. Recent N-body methods are based on an adaptive tree structure. The tree must be built and maintained across physically distributed memory; moreover, the communication requirements are irregular and adaptive. Together with the need to balance the computational work-load among processors, these issues pose interesting challenges and tradeoffs for high-performance implementation. Our implementation was guided by the need to keep solutions simple and general. We use a technique for implicitly representing a dynamic global tree across multiple processors which substantially reduces the programming complexity as well as the performance overheads of distributed memory architectures. The contributions include methods to vectorize the computation and minimize communication time which are theoretically and experimentally justified. The code has been tested by varying the number and distribution of bodies on different configurations of the Connection Machine CM-5. The overall performance on instances with 10 million bodies is typically over 30% of the peak machine rate. Preliminary timings compare favorably with other approaches. © 1994 ACM.[SDGs]SDG9Forestry; Parallel algorithms; Parallel architectures; Parallel processing systems; Trees (mathematics); Communication time; Computational work; Distributed Memory; Distributed memory architecture; High performance codes; High performance implementations; Multiple processors; Programming complexity; Memory architectureconference paper10.1145/181014.1810812-s2.0-84947725835https://doi.org/10.1145/181014.181081