Performance Analysis and Optimizations of ERO2.0 Fusion Code.

In this paper, we present a thorough performance analysis of a highly parallel Monte Carlo code for modeling global erosion and redeposition in fusion devices, ERO2.0. The study shows that the main bottleneck preventing the code from efficiently using the resources is the load imbalance at different levels. Load imbalance is inherent to the problem being solved, particle transport, and deposition. Based on the findings of the analysis, we also describe optimizations implemented on the code to improve its performance on HPC clusters. The proposed optimizations use MPI and OpenMP features, making them portable across architectures and achieving a 3.34 x speedup with respect to the original code.