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From: jep@oink.UUCP
Newsgroups: comp.lang.c
Subject: Re: Dhrystones
Message-ID: <204@oink.UUCP>
Date: Fri, 4-Dec-87 13:19:22 EST
Article-I.D.: oink.204
Posted: Fri Dec  4 13:19:22 1987
Date-Received: Wed, 9-Dec-87 20:16:46 EST
References: <3368@rosevax.Rosemount.COM>
Reply-To: jep@oink.UUCP (James E. Prior)
Organization: Random Prime Research Institute  Columbus, Ohio
Lines: 35
Keywords: C, performance

In article <3368@rosevax.Rosemount.COM> richw@rosevax.Rosemount.COM (Rich Wagenknecht) writes:
>Could somemone tell me what a 'Dhrystone' (<-sp.?) is?
>Why is it used so often to evaluate compiler performance?
>Is it a good overall indicator of compiler peformance?
>
>Thanks in advance,
>Rich W.

First there was the Whetstone benchmark.  It is rich in floating point
calculations, and as such is handy for comparing systems when you are
concerned about scientific calculations.

Most operating system programming doesn't use any floating point math.  Same 
goes for programs such as text editors, compilers, assemblers, linkers, 
and any other program primarily dealing with integers instead of of 
floating point data.  On machines without floating point hardware,
the Whetstone benchmark will report that the machine is very pokey,
even though it might scream when doing operating system stuff or any other
non-floating point calculations.

The Dhrystone benchmark program attempts to measure to speed of non-floating
point code.  As such, it is much better for comparing compilers that the
Whetstone benchmark.

Its name is a pun on "Whet", since it measures the opposite kind
of calculation.

In spite of the above, I am leery of benchmarks.  The is a saying:
"There are lies, damn lies, and benchmarks."

The correct way to compare systems, is to run the programs that *you*
are interested in, on them.  Make sure you are doing emprical bench-
marks, not just paper calculations of how much time it "should" take.
-- 
Jim Prior    jep@oink.UUCP    {ihnp4|cbosgd}!n8emr!oink!jep