Accelerating the cryo-EM structure determination in RELION on GPU cluster.

The cryo-electron microscopy (cryo-EM) is one of the most powerful technologies available today for structural biology. The RELION (Regularized Likelihood Optimization) implements a Bayesian algorithm for cryo-EM structure determination, which is one of the most widely used software in this field. Many researchers have devoted effort to improve the performance of RELION to satisfy the analysis for the ever-increasing volume of datasets. In this paper, we focus on performance analysis of the most time-consuming computation steps in RELION and identify their performance bottlenecks for specific optimizations. We propose several performance optimization strategies to improve the overall performance of RELION, including optimization of expectation step, parallelization of maximization step, accelerating the computation of symmetries, and memory affinity optimization. The experiment results show that our proposed optimizations achieve significant speedups of RELION across representative datasets. In addition, we perform roofline model analysis to understand the effectiveness of our optimizations.