/*
* Print the gettimeofday() clock resolution for this machine.
*
* Code taken from Iozone. Iozone Filesystem Benchmark
* Author: Don Capps
*
*/
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#define THISVERSION " Version $Revision: 1.2 $"
double time_res,delay;
void get_resolution(); /* Works with most compilers */
static double time_so_far1(); /* Works with most compilers */
/*
* Measure and print the gettimeofday() resolution.
*/
main()
{
printf("\n\nMeasuring the gettimeofday() resolution\n\n");
get_resolution();
printf("Time resolution of gettimeofday() = %f seconds\n",time_res);
printf("Time resolution of gettimeofday() = %f milli seconds\n",
time_res*1000);
printf("Time resolution of gettimeofday() = %f micro seconds\n\n",
time_res*(1000*1000));
printf("Provided, courtesy of Iozone. http://www.iozone.org\n\n");
}
/*
* Lifted code from Iozone.
*/
#ifdef HAVE_ANSIC_C
void
get_resolution(void)
#else
void
get_resolution()
#endif
{
double starttime, finishtime;
long j;
again:
finishtime=time_so_far1(); /* Warm up the instruction cache */
starttime=time_so_far1(); /* Warm up the instruction cache */
delay=j=0; /* Warm up the data cache */
while(1)
{
starttime=time_so_far1();
for(j=0;j< delay;j++)
;
finishtime=time_so_far1();
if(starttime==finishtime)
delay++;
else
break;
}
time_res = (finishtime-starttime)/1000000.0;
}
/*
* Lifted code from Iozone.
*/
/************************************************************************/
/* Time measurement routines. */
/* Return time in microseconds */
/************************************************************************/
#ifdef HAVE_ANSIC_C
static double
time_so_far1(void)
#else
static double
time_so_far1()
#endif
{
/* For Windows the time_of_day() is useless. It increments in 55 milli second */
/* increments. By using the Win32api one can get access to the high performance */
/* measurement interfaces. With this one can get back into the 8 to 9 */
/* microsecond resolution. */
#ifdef Windows
LARGE_INTEGER freq,counter;
double wintime;
double bigcounter;
QueryPerformanceFrequency(&freq);
QueryPerformanceCounter(&counter);
bigcounter=(double)counter.HighPart *(double)0xffffffff +
(double)counter.LowPart;
wintime = (double)(bigcounter/(double)freq.LowPart);
return((double)wintime*1000000.0);
#else
#if defined (OSFV4) || defined(OSFV3) || defined(OSFV5)
struct timespec gp;
if (getclock(TIMEOFDAY, (struct timespec *) &gp) == -1)
perror("getclock");
return (( (double) (gp.tv_sec)*1000000.0) +
( ((float)(gp.tv_nsec)) * 0.001 ));
#else
struct timeval tp;
if (gettimeofday(&tp, (struct timezone *) NULL) == -1)
perror("gettimeofday");
return ((double) (tp.tv_sec)*1000000.0) +
(((double) tp.tv_usec) );
#endif
#endif
}