Logo Search packages:      
Sourcecode: x86info version File versions

MHz.c

/*
 *  $Id: MHz.c,v 1.3 2003/06/09 22:02:36 davej Exp $
 *  This file is part of x86info.
 *  (C) 2001 Dave Jones.
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *
 * Estimate CPU MHz routine by Andrea Arcangeli <andrea@suse.de>
 * Small changes by David Sterba <sterd9am@ss1000.ms.mff.cuni.cz>
 *
 */

#include <stdio.h>
#include <sys/time.h>
#include <string.h>
#include <unistd.h>

#ifdef __WIN32__
#include <windows.h>

__inline__ unsigned long timer_init();
#endif /* __WIN32__ */

#include "../x86info.h"

__inline__ unsigned long long int rdtsc()
{
      unsigned long long int x;
      __asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
      return x;
}

void estimate_MHz(struct cpudata *cpu)
{
#ifndef __WIN32__
      struct timezone tz;
      struct timeval tvstart, tvstop;
#endif /* __WIN32__ */
      unsigned long long int cycles[2]; /* gotta be 64 bit */
      unsigned long microseconds; /* total time taken */
      unsigned long eax, ebx, ecx, edx;
      unsigned long freq = 1;

#ifdef __WIN32__
      LARGE_INTEGER lfreq;

      QueryPerformanceFrequency(&lfreq);
      freq = lfreq.LowPart/1000000;
#endif /* __WIN32__ */

      /* Make sure we have a TSC (and hence RDTSC) */
      cpuid (cpu->number, 1, &eax, &ebx, &ecx, &edx);
      if ((edx & (1<<4))==0) {
            printf ("No TSC, MHz calculation cannot be performed.\n");
            cpu->MHz = 0;
            return;
      }

#ifdef __WIN32__
      timer_init();
      cycles[0] = rdtsc();
      microseconds = timer_init();
#else
      memset(&tz, 0, sizeof(tz));

      /* get this function in cached memory */
      gettimeofday(&tvstart, &tz);
      cycles[0] = rdtsc();
      gettimeofday(&tvstart, &tz);
#endif /* __WIN32__ */

      /* we don't trust that this is any specific length of time */
      usleep(250000);
      
#ifdef __WIN32__
      timer_init();
      cycles[1] = rdtsc();
      microseconds = timer_init() - microseconds;
#else
      gettimeofday(&tvstop, &tz);
      cycles[1] = rdtsc();
      gettimeofday(&tvstop, &tz);

      microseconds = ((tvstop.tv_sec-tvstart.tv_sec)*1000000) +
            (tvstop.tv_usec-tvstart.tv_usec);
#endif /* __WIN32__ */

      cpu->MHz = (int) (cycles[1]-cycles[0]) / (microseconds/freq);


      if ((cpu->MHz % 50) > 15)
            cpu->MHz = ((cpu->MHz / 50) * 50) + 50;
      else
            cpu->MHz = ((cpu->MHz / 50) * 50);

}

#ifdef __WIN32__
__inline__ unsigned long timer_init()
{
      LARGE_INTEGER lcnt;

      QueryPerformanceCounter(&lcnt);

      return lcnt.LowPart;
}
#endif /* __WIN32__ */


Generated by  Doxygen 1.6.0   Back to index