Empirical study of dynamic scheduling on rings of processors

Miranda E. Barrows, Dawn E. Gregory, Lixin Gao, Arnold L. Rosenberg, Paul R. Cohen

Research output: Contribution to journalArticlepeer-review


We empirically analyze and compare two low-overhead, deterministic policies for scheduling dynamically evolving tree-structured computations on rings of identical processing elements (PEs). Our computations have each task either halt or spawn two independent children and then halt; they abstract, for instance, computations generated by multigrid methods. Our simpler policy, KOSO, has each PE keep one child of a spawning task and pass the other to its clockwise neighbor in the ring; our more sophisticated policy, KOSO*, operates similarly, but allows child-passing only from a more heavily loaded PE to a more lightly loaded one. Both policies execute waiting tasks in increasing order of their depths in the evolving task-tree. Our study focuses on two conjectures: (a) Both policies yield good parallel speedup on large classes of the computations we study. (b) Policy KOSO* outperforms policy KOSO in many important situations. We verify these conjectures via a suite of experiments, supplemented by supporting mathematical analyses. We view our methodology of experimental design and analysis as a major component of our study's contribution, which will prove useful in other such studies.

Original languageEnglish (US)
Pages (from-to)1063-1079
Number of pages17
JournalParallel Computing
Issue number9
StatePublished - Sep 1999
Externally publishedYes

ASJC Scopus subject areas

  • Software
  • Theoretical Computer Science
  • Hardware and Architecture
  • Computer Networks and Communications
  • Computer Graphics and Computer-Aided Design
  • Artificial Intelligence


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