Arepo-RT: Moving Mesh Radiation Hydrodynamics with GPU Acceleration

25 Sept 2024

Speaker: Oliver Zier (CFA Harvard)

Abstract:

Radiative transfer (RT) is essential for modeling many astrophysical phenomena, but its integration into radiation-hydrodynamics (RHD) simulations is computationally intensive due to the stringent time-stepping and high dimensionality requirements. The emergence of exascale supercomputers, equipped with extensive CPU cores and GPU accelerators, offers new avenues for optimizing these simulations. This talk will outline our progress in adapting Arepo-RT for exascale environments. Key advancements include a new node-to-node communication strategy utilizing shared memory, which significantly reduces intra-node communication overhead by leveraging direct memory access. By consolidating inter-node messages, we increase network bandwidth utilization, improving performance on both large-scale and smaller-scale systems. Additionally, transitioning RT calculations to GPUs has led to a speedup of approximately 15 times for standard benchmarks. As a case study, cosmological RHD simulations of the Epoch of Reionization demonstrate a threefold improvement in efficiency without requiring modifications to the core Arepo codebase. These developments have broad implications for the scalability and efficiency of future astrophysical simulations, offering a framework for porting similar simulation codes based on unstructured resolution elements to GPU-centric architectures.