Porting HPC Applications to AMD Instinct$^\text{TM}$ MI300A Using Unified Memory and OpenMP

TL;DR

This paper demonstrates how to port HPC applications to AMD MI300A APUs using unified memory and OpenMP, simplifying development and improving performance for data center workloads.

Contribution

It provides a programming blueprint leveraging unified memory and OpenMP 5.2 for AMD MI300A APUs, highlighting differences from traditional GPU approaches.

Findings

Unified memory simplifies application development.

OpenFOAM was successfully ported to MI300A using OpenMP.

The approach enhances performance and maintainability.

Abstract

AMD Instinct$^\text{TM}$ MI300A is the world's first data center accelerated processing unit (APU) with memory shared between the AMD "Zen 4" EPYC$^\text{TM}$ cores and third generation CDNA$^\text{TM}$ compute units. A single memory space offers several advantages: i) it eliminates the need for data replication and costly data transfers, ii) it substantially simplifies application development and allows an incremental acceleration of applications, iii) is easy to maintain, and iv) its potential can be well realized via the abstractions in the OpenMP 5.2 standard, where the host and the device data environments can be unified in a more performant way. In this article, we provide a blueprint of the APU programming model leveraging unified memory and highlight key distinctions compared to the conventional approach with discrete GPUs. OpenFOAM, an open-source C++ library for computational fluid dynamics, is presented as a case study to emphasize the flexibility and ease of offloading a full-scale production-ready application on MI300 APUs using directive-based OpenMP programming.