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Subject: system timer too fast on AMD64 / Gentoo Linux

Author: James Swafford

Date: 19:20:20 02/16/06


While testing Prophet on my wife's new AMD64 I noticed test suites
finished too fast.  Using either the MilliTimer() or gettime()
methods below, the program finishes in about 5 seconds, when it
should take 10.

Anyone know why, or what I can do to fix this?  Since I'm only using
this machine for CCT, I could hack up a kludge, but I'm more
interested in the cause.

I'm using Gentoo Linux 2.6.15 for AMD64.
--
James


#include <stdlib.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/timeb.h>

int MilliTimer(void)
{
   struct timeb t;
   ftime(&t);
   return (t.time*1000)+t.millitm;
}

int gettime(void)
{
   timeval te;
   gettimeofday(&te,NULL);
   int t = te.tv_sec;
   return t * 1000 + te.tv_usec/1000;
}

int main() {
   int start_time = gettime();
   printf("start: %d\n",start_time);
   while (gettime() - start_time < 10000);

   printf("end: %d\n",gettime());
   return 0;
}




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