Exploiting inter-file access patterns using multi-collective I/O

  • Authors:
  • Gokhan Memik;Mahmut Kandemir;Alok Choudhary

  • Affiliations:
  • EE Dept., UCLA;CSE Dept., Penn State;ECE Dept., Northwestern University

  • Venue:
  • FAST'02 Proceedings of the 1st USENIX conference on File and storage technologies
  • Year:
  • 2002

Quantified Score

Hi-index 0.00

Visualization

Abstract

This paper introduces a new concept called Multi-Collective I/O (MCIO) that extends conventional collective I/O to optimize I/O accesses to multiple arrays simultaneously. In this approach, as in collective I/O, multiple processors co-ordinate to perform I/O on behalf of each other if doing so improves overall I/O time. However, unlike collective I/O, MCIO considers multiple arrays simultaneously; that is, it has a more global view of the overall I/O behavior exhibited by application. This paper shows that determining optimal MCIO access pattern is an NP-complete problem, and proposes two different heuristics for the access pattern detection problem (also called the assignment problem). Both of the heuristics have been implemented within a runtime library, and tested using a large-scale scientific application. Our preliminary results show that MCIO outperforms collective I/O by as much as 87%. Our runtime library-based implementation can be used by users as well as optimizing compilers. Based on our results, we recommend future library designers for I/O-intensive applications to include MCIO in their suite of optimizations.