Basic HTML version of Foils prepared 26 September 1996

Foil 114 The INDEPENDENT Assertion in HPF

From HPCC Software Technologies Fall 96 -- Overview and HPF Delivered Lectures of CPS615 Basic Simulation Track for Computational Science -- 26 September 96. by Geoffrey C. Fox


!HPF$ INDEPENDENT [ ,NEW (variable-list) ]
INDEPENDENT asserts that no iteration affects any other in any way
It implements the "embarassingly parallel" problem class we discussed under structure of problems
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
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
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
HPF2 (see later) has extra feature of allowing REDUCTION (accumulated) variables in INDEPENDENT DO loops



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