SAFETY AND OPTIMIZATION TRANSFORMATIONS FOR DATA FLOW PROGRAMS

  • Authors:
  • L. B. Montz

  • Affiliations:
  • -

  • Venue:
  • SAFETY AND OPTIMIZATION TRANSFORMATIONS FOR DATA FLOW PROGRAMS
  • Year:
  • 1980

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Abstract

The data flow concept of computation seeks to achieve high performance by allowing concurrent execution of instructions based on the availability of data. This thesis explores the translation of a subset of the high level languages VAL to data flow graphs. The major problem in performing this translation for the target machine, the Dennis-Misunas data flow computer, stems from the restriction that graph execution sequences place at most one value on any given arc at any time. The data / acknowledge are pair transformation is introduced as a means of implementing this required operational behavior. Its effect on data flow graph operation is subsequently explored as it relates to correctness and performance. Through the arc transformation enables graphs to be executed without the possibility of deadlock, the resulting overhead and the potential loss of some concurrency represent significant costs. Two techniques aimed at minimizing these problems are developed for optimizing transformed graphs. The optimization to eliminate unneeded acknowledge arcs analyzes VAL constructs to identify arc pairs which permit removal of their acknowledge arc. The optimization to balance token flow specifies a method of inserting identity operators into a graph for the purpose of pipelining input sets, and thereby increasing graph throughput. Though developed within the context noted, the translation and optimization issues described should prove applicable to other data flow architectures.