Distributed Cell Set : A Library for Space-Dependent Communication/Computation Overlap on Manycore Cluster
Yoshiki Kawanishi, Patrick C. Finnerty, Tomio Kamada, Chikara Ohta · 2023
The increase in the number of cores available in modern processors makes it important for implementations to maximize their use within a node by overlapping communication and computation. However, when the dependencies between communication and computation are complex and evolve over the course of the execution, their implementation becomes tedious and may lead to bugs. In this paper, we focus on spatial simulation where elements move over time due to interactions with other surrounding elements. We propose a Distributed Cell Set Library that manages the distribution of the simulation space using unit areas (cell units). We make it possible to manage the granularity with which cell communication may overlap with computation, and for multithreaded computation. In addition, we make it possible to describe the relationships between inter-node communication and the pending computation in cell units. For evaluation, we introduce the implementation of a two-dimensional molecular dynamics simulation using our library. We show that using our computation and communication overlapping method, the delays to reach global synchronization that are necessary in the original implementation can be avoided.