GBIS Benchmark Header File: tick1


   ==================================================================
   ===                                                            ===
   ===          GENESIS / PARKBENCH Parallel Benchmarks           ===
   ===                                                            ===
   ===                           TICK1                            ===
   ===                                                            ===
   ===               Measure the clock tick interval              ===
   ===               Measure the clock resolution                 ===
   ===                                                            ===
   ===               Versions:  Std F77, Subset HPF (F90)         ===
   ===                                                            ===
   ===        Original Author:  Roger Hockney                     ===
   ===                          Department of Electronics and     ===
   ===                          Computer Science                  ===
   ===                          University of Southampton         ===
   ===                          Southampton SO17 1BJ, UK          ===
   ===                                                            ===
   ===       Modifications by:  Ian Glendinning                   ===
   ===                          Southampton HPC Centre            ===
   ===                          Computing Services                ===
   ===                          University of Southampton         ===
   ===                          Southampton SO17 1BJ, UK          ===
   ===                                                            ===
   ===     fax.:+44-703-593939   e-mail:support@par.soton.ac.uk   ===
   ===                                                            ===
   ===          Last update: May 1994                             ===
   ===                                                            ===
   ==================================================================


1. Description
--------------

This benchmark is used to estimate the resolution of the clock tick for
system timing routines. The benchmark output gives an upper bound (the 
worst case) for the resolution of the system clock used to provide 
timing information for the other benchmarks in the suite. It is 
essential to be aware of the resolution of the system clock in making 
measurements with some of the applications kernels where the time for 
the execution of the kernel may be comparable with the clock tick time. 
In such cases sufficient accuracy is obtained by surrounding the kernel 
by a repeat loop. The measurement of the clock resolution then gives a
guide to how many repeats are needed to achieve a specified accuracy
in the timing.

Usually the timers to be found in system libraries have a tick less or
equal to 10 milliseconds. The output from the TICK1 benchmark is the
upper bound (the worst case) of the system's time tick.


2. Operating Instructions
-------------------------

To compile and link the benchmark type:   `make'.  On some systems
it may be necessary to allocate the appropriate resources before running
the benchmark, eg. on the iPSC/860 to reserve a single processor, 
type:    getcube -t1. 

To run the benchmark type:     tick1

Output from the benchmark is written to the screen and saved in the 
file "tick1.res".  In addition to the value obtained for the clock tick,
the first fifty time differences are written to the file.

$Id: ReadMe,v 1.3 1994/05/31 16:20:07 igl Exp igl $

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High Performance Computing Centre

Submitted by Mark Papiani,
last updated on 10 Jan 1995.