Blocking Versus Non-Blocking Halo Exchange

TL;DR

This paper presents a non-blocking halo exchange routine for lattice Boltzmann simulations, demonstrating its performance benefits and potential for work-communication overlap on high-performance computing systems.

Contribution

It introduces a novel non-blocking halo exchange method that allows work-communication overlap, improving efficiency in parallel lattice Boltzmann computations.

Findings

Non-blocking routine performs well without overlap.

Work-communication overlap enhances performance.

Benchmarking on ARCHER shows promising results.

Abstract

This report describes the design, implementation and analysis of a non-blocking halo exchange routine as an alternative to the blocking halo exchange routine in the lattice Boltzmann code Ludwig. The alternative, non-blocking, routine is implemented in such a way to allow work-communication overlap. Detailed benchmarks in this report show that the non-blocking version is a good alternative even without any work-communication overlap. Work-Communication overlap can be used to improve the performance of the non-blocking routine. Development and benchmarking were conducted on the UK national supercomputer, ARCHER.