Layout-aware scientific computing: a case study using MILC

Nowadays, high performance computers have more cores and nodes than ever before. Computation is spread out among them, leading to more communication. For this reason, communication can easily become the bottleneck of a system and limit its scalability. The layout of an application on a computer is the key factor to preserve communication locality and reduce its cost. In this paper, we propose a simple model to optimize the layout for scientific applications by minimizing inter-node communication cost. The model takes into account the latency and bandwidth of the network and associates them with the dominant layout variables of the application. We take MILC as an example and analyze its communication patterns. According to our experimental results, the model developed for MILC achieved a satisfactory accuracy for predicting the performance, leading to up to 31% performance improvement.