Communication Pre-evaluation in HPF

Pierre Boulet ^*   Xavier Redon ^#

Abstract: Parallel computers are difficult to program efficiently. We believe that a good way to help programmers write efficient programs is to provide them with tools that show them how their programs behave on a parallel computer. Data distribution is the major performance factor of data-parallel programs and so automatic data layout for High Performance Fortran programs has been studied by many researchers recently. The communication volume induced by a data distribution is a good estimator of the efficiency of this data distribution.

We present here a symbolic method to compute the communication volume generated by a given data distribution during the program writing phase (before compilation). We stay machine-independent to assure portability. Our goal is to help the programmer understand the data movements its program generates and thus find a good data distribution. Our method is based on parametric polyhedral computations. It can be applied to a large class of regular codes.

• Introduction
• Related Work
• Description of the Problem
  • General Remarks
  • Modelization
• Algebraic Method to Evaluate HPF Communications
  • Formula for Communication Cost Evaluation
  • Formal Representation of HPF Alignments
  • Enumeration of Operations in the Template Iteration Space
  • Formal Representation of HPF Distributions
• Tools for the Evaluation of HPF Communications
  • Manipulation of Polyhedra
  • Using the PIP Software to Compute Inclusion
  • Counting the Elements of the Communication Set
• Conclusion
• References

This document was translated from L^AT_EX by H^EV^EA and H^AC^HA.