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Scalability Evaluation of Barrier Algorithms for OpenMP

  • Ramachandra Nanjegowda
  • Oscar Hernandez
  • Barbara Chapman
  • Haoqiang H. Jin
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5568)

Abstract

OpenMP relies heavily on barrier synchronization to coordinate the work of threads that are performing the computations in a parallel region. A good implementation of barriers is thus an important part of any implementation of this API. As the number of cores in shared and distributed shared memory machines continues to grow, the quality of the barrier implementation is critical for application scalability. There are a number of known algorithms for providing barriers in software. In this paper, we consider some of the most widely used approaches for implementing barriers on large-scale shared-memory multiprocessor systems: a ”blocking” implementation that de-schedules a waiting thread, a ”centralized” busy wait and three forms of distributed ”busy” wait implementations are discussed. We have implemented the barrier algorithms in the runtime library associated with a research compiler, OpenUH. We first compare the impact of these algorithms on the overheads incurred for OpenMP constructs that involve a barrier, possibly implicitly. We then show how the different barrier implementations influence the performance of two different OpenMP application codes.

Keywords

Centralize Blocking Parallel Region Barrier Implementation Barrier Synchronization Schedule Overhead 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Liao, C., Hernandez, O., Chapman, B., Chen, W., Zheng, W.: Openuh: An optimizing, portable openmp compiler. In: 12th Workshop on Compilers for Parallel Computers (January 2006)Google Scholar
  2. 2.

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Ramachandra Nanjegowda
    • 1
  • Oscar Hernandez
    • 1
  • Barbara Chapman
    • 1
  • Haoqiang H. Jin
    • 2
  1. 1.Computer Science DepartmentUniversity of HoustonHoustonUSA
  2. 2.NASA Ames Research CenterMoffett FieldUSA

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