Demystifying asynchronous I/O Interference in HPC applications

Shu Mei Tseng, Bogdan Nicolae, Franck Cappello, Aparna Chandramowlishwaran

Research output: Contribution to journalArticlepeer-review

Abstract

With increasing complexity of HPC workflows, data management services need to perform expensive I/O operations asynchronously in the background, aiming to overlap the I/O with the application runtime. However, this may cause interference due to competition for resources: CPU, memory/network bandwidth. The advent of multi-core architectures has exacerbated this problem, as many I/O operations are issued concurrently, thereby competing not only with the application but also among themselves. Furthermore, the interference patterns can dynamically change as a response to variations in application behavior and I/O subsystems (e.g. multiple users sharing a parallel file system). Without a thorough understanding, I/O operations may perform suboptimally, potentially even worse than in the blocking case. To fill this gap, this paper investigates the causes and consequences of interference due to asynchronous I/O on HPC systems. Specifically, we focus on multi-core CPUs and memory bandwidth, isolating the interference due to each resource. Then, we perform an in-depth study to explain the interplay and contention in a variety of resource sharing scenarios such as varying priority and number of background I/O threads and different I/O strategies: sendfile, read/write, mmap/write underlining trade-offs. The insights from this study are important both to enable guided optimizations of existing background I/O, as well as to open new opportunities to design advanced asynchronous I/O strategies.

Original languageEnglish (US)
Pages (from-to)391-412
Number of pages22
JournalInternational Journal of High Performance Computing Applications
Volume35
Issue number4
DOIs
StatePublished - Jul 2021
Externally publishedYes

Keywords

  • asynchronous and concurrent I/O
  • checkpointing
  • HPC applications
  • I/O interference
  • performance analysis

ASJC Scopus subject areas

  • Software
  • Theoretical Computer Science
  • Hardware and Architecture

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