Switch-stacks: a scheme for microtasking nested parallel loops

  • Authors:
  • Jyh-Herng Chow;Williams Ludwell Harrison, III

  • Affiliations:
  • Center for Supercomputing Research and Development, University of Illinois at Urbana-Champaign, Urbana, IL;Center for Supercomputing Research and Development, University of Illinois at Urbana-Champaign, Urbana, IL

  • Venue:
  • Proceedings of the 1990 ACM/IEEE conference on Supercomputing
  • Year:
  • 1990

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Abstract

This paper discusses run-time microtasking support for executing nested parallel loops on a shared memory multiprocessor system, and presents a new scheme called switch-stacks for implementing such support. We first discuss current approaches to flat microtasking, and investigate how to extend these for full microtasking. We point out the problem of dummy waiting in the processor that initiates a parallel loop. To solve this problem, two schemes, dequeue-tasks and dequeue-descendant-tasks are considered and their disadvantages are discussed. The switch-stacks scheme we proposed perfectly solves the problem. These schemes have been implemented in the PARCEL run-time system. The results show that the new scheme achieves the best performance in execution time and stability nearly always.