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Date: Thu, 08 Jul 2004 05:20:45 -0700
To: "Alex Vinokur" <alexvn AT connect DOT to>, cygwin AT cygwin DOT com
From: Tim Prince <tprince AT computer DOT org>
Subject: Re: What does clock() return?
In-Reply-To: <cciguv$e7o$1@sea.gmane.org>
References: <cciguv$e7o$1 AT sea DOT gmane DOT org>
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At 09:01 PM 7/7/2004, Alex Vinokur wrote:

>Here is an article 
>http://groups.google.com/groups?selm=2l2ucgF7jv50U1%40uni-berlin.de
>from http://groups.google.com/groups?group=microsoft.public.vc.language
>
>
>"Victor Bazarov" <v DOT Abazarov AT comAcast DOT net> wrote in message 
>news:%23gH7pzEZEHA DOT 992 AT TK2MSFTNGP10 DOT phx DOT gbl...
> > Is it a known issue that in VC++ RTL the function 'clock()'
> > reports the wall clock instead of CPU time used?  I ran this
> > test program on Windows and Unix:

A long standing "problem."  As Win9x had no choice other than wall clock 
time, MSVCRTL gives you no choice.  Other compiler vendors make the choice 
according to which version of Windows is running.  If you choose 
ProcessTime(), the resolution is 0.010 seconds, which is unsatisfactory for 
many small benchmarks, so then we must over-ride it by using the rdtsc 
counter directly.

Here is my understanding of the decision:  for cygwin, the primary goal is 
compatibility with gcc running on other OS.  For mingw, the goal is 
compatibility with Microsoft practice, where feasible.  Thus, no chance of 
compatibility between mingw and cygwin on this point.



Tim Prince 


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