  Neighbor search is of fundamental important to many engineering and science
fields such as physics simulation and computer graphics. This paper proposes to
formulate neighbor search as a ray tracing problem and leverage the dedicated
ray tracing hardware in recent GPUs for acceleration. We show that a naive
mapping under-exploits the ray tracing hardware. We propose two performance
optimizations, query scheduling and query partitioning, to tame the
inefficiencies. Experimental results show 2.2X -- 65.0X speedups over existing
neighbor search libraries on GPUs. The code is available at
https://github.com/horizon-research/rtnn.
