Communication-Efficient Parallel Sorting

  • Authors:
  • Michael T. Goodrich

  • Affiliations:
  • -

  • Venue:
  • SIAM Journal on Computing
  • Year:
  • 1999

Quantified Score

Hi-index 0.00

Visualization

Abstract

We study the problem of sorting n numbers on a p-processor bulk-synchronous parallel (BSP) computer, which is a parallel multicomputer that allows for general processor-to-processor communication rounds provided each processor sends and receives at most h items in any round. We provide parallel sorting methods that use internal computation time that is $O({n\log n \over p})$ and a number of communication rounds that is $O({\log n \over \log (h+1)})$ for $h=\Theta(n/p)$. The internal computation bound is optimal for any comparison-based sorting algorithm. Moreover, the number of communication rounds is bounded by a constant for the (practical) situations when $p\le n^{1-{1/c}}$ for a constant $c\ge 1$. In fact, we show that our bound on the number of communication rounds is asymptotically optimal for the full range of values for p, for we show that just computing the "or" of n bits distributed evenly to the first O(n/h) of an arbitrary number of processors in a BSP computer requires $\Omega(\log n/\log (h+1))$ communication rounds.