Abstract:

We present the newly developed code, GAMER (GPU-accelerated Adaptive MEsh Refinement
code), which has adopted a novel approach to improve the performance of adaptive mesh refinement
(AMR) astrophysical simulations by a large factor with the use of the graphic processing
unit (GPU). The AMR implementation is based on a hierarchy of grid patches with an oct-tree
data structure. We adopt a three-dimensional relaxing TVD scheme for the hydrodynamic solver,
and a multi-level relaxation scheme for the Poisson solver. Both solvers have been implemented
in GPU, by which hundreds of patches can be advanced in parallel. The computational overhead
associated with the data transfer between CPU and GPU is carefully reduced by utilizing the
capability of asynchronous memory copies in GPU, and the computing time of the ghost-zone
values for each patch is made to diminish by overlapping it with the GPU computations. We
demonstrate the accuracy of the code by performing several standard test problems in astrophysics.
GAMER is a parallel code that can be run in a multi-GPU cluster system. We measure
the performance of the code by performing purely-baryonic cosmological simulations in different
hardware implementations, in which detailed timing analyses provide comparison between the
computations with and without GPU(s) acceleration. Maximum speed-up factors of 12.19 and
10.47 are demonstrated using 1 GPU with 40963 effective resolution and 16 GPUs with 81923
effective resolution, respectively.