TUNING

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Performance tuning and setting up the input data file hpcg.dat
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Current as of release HPCG - 3.0 - November 11, 2015

Check  the  website  http://hpcg-benchmark.org/ for  the latest
information.

After  building  the executable hpcg_build/bin/xhpcg, (where hpcg_build is your
build directory for HPCG) one  may want  to  modify the
input  data  file  hpcg.dat.  This file should  reside  in  the  same directory
as  the  executable hpcg_build/bin/xhpcg.   An  example  hpcg.dat  file is provided
by default.  This  file  contains  information about the problem sizes,
machine configuration,  and  algorithm features to be used by the executable.
It is 4 lines long. All the selected parameters  will  be  printed in the
output generated by the executable.

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Description of the hpcg.dat file
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* Line 1: (unused) Typically  one  would  use this line for its own good. For
example, it could be used to summarize the con- tent of the input file. By
default this line reads:

HPCG benchmark input file

* Line 2: (unused) same as Line 1. By default, this line reads:

Sandia National Laboratories; University of Tennessee, Knoxville

* Line 3: This line specifies the local (to an MPI process) dimensions of the
problem. By default, this line reads:

104 104 104

which means that each MPI process will be computing a solution for a cube of
size 104 points.

* Line 4: This line specifies the number of seconds of how long the timed
portion of the benchmark should run. By default, this line reads:

60

which means that the timed portion of the benchmark will run 1 minute.
This length of time is not sufficient for submitting an official run
but does give sufficient data for tuning the benchmark in most cases.