Basic HTML version of Foils prepared 17 Sept 1996

Foil 70 The INDEPENDENT Assertion in HPF

From New CPS615HPF and Fortran90 Discussion Sept 17 96 Basic Simulation Track for Computational Science CPS615 -- Fall Semester 96. by Geoffrey C. Fox, Tom Haupt
1 !HPF$ INDEPENDENT [ ,NEW (variable-list) ]
2 INDEPENDENT asserts that no iteration affects any other in any way
3 It implements the "embarassingly parallel" problem class we discussed under structure of problems
4 Note rest of HPF tackles mainly the synchronous problem class with some loosely synchronous capability
  • HPF2 has "tasking" for metaproblem class and some extensions for further irregular loosely synchronous problems
5 NEW variables are defined to have fresh instantiations for each iteration as is typically needed for embarassingly parallel problems where in fact essentially all variables in a loop would be NEW
6 Note INDEPENDENT can be applied to FORALL and asserts that no index point assigns to any location that another iteration index value uses
  • This reduces copying needed in FORALL by COMPILER
7 HPF2 (see later) has extra feature of allowing REDUCTION (accumulated) variables in INDEPENDENT DO loops
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© on Tue Oct 7 1997