A Task Programming Implementation for the Particle in Cell Code Smilei

TL;DR

This paper introduces a task-based implementation of the Particle in Cell loop in Smilei, leveraging OpenMP to improve load balancing and scaling in plasma physics simulations.

Contribution

It presents a novel task programming approach for the PIC loop in Smilei, enhancing asynchronous execution and load balancing using OpenMP.

Findings

Improved load balancing in PIC simulations

Enhanced strong scaling performance

Mitigation of thread-level load imbalance

Abstract

An implementation of the electromagnetic Particle in Cell loop in the code Smilei using task programming is presented. Through OpenMP, the macro-particles operations are formulated in terms of tasks. This formulation allows asynchronous execution respecting the data dependencies of the macro-particle operations, the most time-consuming part of the code in simulations of interest for plasma physics. Through some benchmarks it is shown that this formulation can help mitigating the load imbalance of these operations at the OpenMP thread level. The improvements in strong scaling for load-imbalanced physical cases are discussed.