A macrotask-level unlimited speculative execution on multiprocessors

Hayato Yamana, Mitsuhisa Sato, Yuetsu Kodama, Hirofumi Sakane, Shunichi Sakai, Yoshinori Yamaguchi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)


The purpose of this paper is to propose a new fast execution scheme of FORTRAN programs. The proposed scheme enables the fast initiation of macrotask when its data dependences are satisfied even if the control flow has not been reached. The previous schemes to parallelize a program including conditional branches have a number of problems - 1) Though the theoretical speedup ratio is up to N when N conditional branches are jumped on either a VLIW or a superscalar machine, the number of N is restricted up to the number of ALU's on a chip, 2) Since conventional control schemes use a few processors to control macrotasks, the overhead to control them is large. The proposed scheme solves these problems - 1) The proposed scheme enables speculative execution between coarse grain tasks, i.e., macrotasks, on multiprocessors by jumping many conditional branches, 2) A distributed control scheme is proposed and implemented on the EM-4 multiprocessor to decrease the control overhead of macrotasks. Preliminary evaluations show that the control overhead of the proposed scheme is smaller than that of the other control schemes. Moreover, it is confirmed that the distributed control can be implemented by using software when the average macrotask execution time is larger than 14.4 (Is on the EM-4 multiprocessor.

Original languageEnglish
Title of host publicationProceedings of the 9th International Conference on Supercomputing, ICS 1995
PublisherAssociation for Computing Machinery
Number of pages10
ISBN (Electronic)0897917286
Publication statusPublished - 1995 Jul 3
Externally publishedYes
Event9th International Conference on Supercomputing, ICS 1995 - Barcelona, Spain
Duration: 1995 Jul 31995 Jul 7

Publication series

NameProceedings of the International Conference on Supercomputing
VolumePart F129361


Conference9th International Conference on Supercomputing, ICS 1995


  • Compiler
  • Distributed control
  • Macrotask
  • Multiprocessor
  • Parallel processing
  • Speculation
  • Speculative execution

ASJC Scopus subject areas

  • General Computer Science


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