SPARTA: Spatial Acceleration for Efficient and Scalable Horizontal Diffusion Weather Stencil Computation

Abstract

Fast and accurate climate simulations and weather predictions are critical for understanding and preparing for the impact of climate change. Real-world climate and weather simulations involve the use of complex compound stencil kernels, which are composed of a combination of different stencils. Horizontal diffusion is one such important compound stencil found in many climate and weather prediction models. Its computation involves a large amount of data access and manipulation that leads to two main issues on current computing systems. First, such compound stencils have high memory bandwidth demands as they require large amounts of data access. Second, compound stencils have complex data access patterns and poor data locality, as the memory access pattern is typically irregular with low arithmetic intensity. As a result, state-of-the-art CPU and GPU implementations suffer from limited performance and high energy consumption. Recent works propose using FPGAs as an alternative to traditional CPU and GPU-based systems to accelerate weather stencil kernels. However, we observe that stencil computation cannot leverage the bit-level flexibility available on an FPGA because of its complex memory access patterns, leading to high hardware resource utilization and low peak performance.