Optimization of the parallel semi‐Lagrangian scheme based on overlapping communication with computation in the YHGSM

Abstract

AbstractThe Yi‐he global spectral model (YHGSM) is a numerical weather prediction (NWP) model developed by the National University of Defense Technology, China. The YHGSM has two optimization techniques that have recently been adopted for the on‐demand communication version of the semi‐Lagrangian scheme: one‐sided communication and an adaptive strategy for the maximum wind speed. However, the limitation of the original model is that the computation and communication cannot be performed simultaneously, resulting in a waste of resources. This article addresses this limitation by dividing the array to be interpolated into three independent subarrays. The communication and interpolation operations for each subarray are rearranged into three groups. This allows the overlap of the communication with computation between different groups. In addition, by adjusting the synchronization operations, the degree of overlap is further increased. In the optimized scheme, the per‐step overhead of the interpolation phase is greatly reduced, and its speedup decreases first and increases afterwards with the increase of the number of cores. Therefore, when the number of cores is large, the benefits from overlapping the communication with computation will be more substantial.