Optimizing parallel performance of unstructured volume rendering for the earth simulator

A scalable and high-performance parallel visualization subsystem has been developed in GeoFEM for the Earth Simulator (ES). As part of the ES project in Japan, the proposed subsystem is effective for the visualization of huge-scale unstructured datasets, and can be concurrent with computation on the same high-performance parallel computer. Moreover, some parallel visualization modules have obtained a good parallel performance, covering scalar, vector and tensor fields. This paper will take volume rendering method as an example to describe a number of efficient parallel performance optimization strategies we adopted for large-scale unstructured data visualization on SMP cluster machines, including suitable design of visualization method, the three-level hybrid parallelization which means message passing for inter-SMP node communication, loop directives for intra-SMP node parallelization, and vectorization for each processing element, plus dynamic load balancing. Good visualization images and high parallel performance have been achieved on the ES, thus demonstrating the feasibility and effectiveness of the proposed method.