HPAC-Offload: Accelerating HPC Applications with Portable Approximate Computing on the GPU

TL;DR

This paper introduces HPAC-Offload, a pragma-based programming model that enables portable approximate computing on GPUs, significantly accelerating HPC applications with minimal quality loss.

Contribution

It presents a novel, portable approach to applying approximate computing techniques on GPUs for HPC, extending OpenMP offload applications.

Findings

AC techniques can accelerate HPC applications by over 1.6x on GPUs

Minimal quality loss of about 0.1% with significant performance gains

Provides insights to guide future GPU-based AC development

Abstract

The end of Dennard scaling and the slowdown of Moore's law led to a shift in technology trends toward parallel architectures, particularly in HPC systems. To continue providing performance benefits, HPC should embrace Approximate Computing (AC), which trades application quality loss for improved performance. However, existing AC techniques have not been extensively applied and evaluated in state-of-the-art hardware architectures such as GPUs, the primary execution vehicle for HPC applications today. This paper presents HPAC-Offload, a pragma-based programming model that extends OpenMP offload applications to support AC techniques, allowing portable approximations across different GPU architectures. We conduct a comprehensive performance analysis of HPAC-Offload across GPU-accelerated HPC applications, revealing that AC techniques can significantly accelerate HPC applications (1.64x LULESH on AMD, 1.57x NVIDIA) with minimal quality loss (0.1%). Our analysis offers deep insights into the performance of GPU-based AC that guide the future development of AC algorithms and systems for these architectures.