An Efficient OpenMP Runtime System for Hierarchical Arch

TL;DR

This paper presents an efficient OpenMP runtime system tailored for hierarchical architectures, leveraging BubbleSched for improved thread and data distribution, resulting in significant speedup enhancements on benchmark applications.

Contribution

It introduces a novel scheduling strategy for nested OpenMP parallelism using BubbleSched, optimizing thread affinity and memory access in hierarchical non-uniform architectures.

Findings

Significant speedup improvements on NAS benchmark applications

Effective thread affinity management using bubbles

Enhanced performance on hierarchical multiprocessor systems

Abstract

Exploiting the full computational power of always deeper hierarchical multiprocessor machines requires a very careful distribution of threads and data among the underlying non-uniform architecture. The emergence of multi-core chips and NUMA machines makes it important to minimize the number of remote memory accesses, to favor cache affinities, and to guarantee fast completion of synchronization steps. By using the BubbleSched platform as a threading backend for the GOMP OpenMP compiler, we are able to easily transpose affinities of thread teams into scheduling hints using abstractions called bubbles. We then propose a scheduling strategy suited to nested OpenMP parallelism. The resulting preliminary performance evaluations show an important improvement of the speedup on a typical NAS OpenMP benchmark application.