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  1. #include <signal.h>
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5. #include <sys/time.h>
  6.  
  7.  
  8. #define USECREQ 250
  9. #define LOOPS   1000
  10.  
  11. void event_handler (int signum)
  12. {
  13.  static unsigned long cnt = 0;
  14.  static struct timeval tsFirst;
  15.  if (cnt == 0) {
  16.    gettimeofday (&tsFirst, 0);
  17.  } 
  18.  cnt ++;
  19.  if (cnt >= LOOPS) {
  20.    struct timeval tsNow;
  21.    struct timeval diff;
  22.    setitimer (ITIMER_REAL, NULL, NULL);
  23.    gettimeofday (&tsNow, 0);
  24.    timersub(&tsNow, &tsFirst, &diff);
  25.    unsigned long long udiff = (diff.tv_sec * 1000000) + diff.tv_usec;
  26.    double delta = (double)(udiff/cnt)/1000000;
  27.    int hz = (unsigned)(1.0/delta);
  28.    printf ("kernel timer interrupt frequency is approx. %d Hz", hz);
  29.    if (hz >= (int) (1.0/((double)(USECREQ)/1000000))) {
  30.      printf (" or higher");
  31.    }       
  32.    printf ("\n");
  33.    exit (0);
  34.  }
  35. }
  36.  
  37. int main (int argc, char **argv)
  38. {
  39.  struct sigaction sa;
  40.  struct itimerval timer;
  41.  
  42.  memset (&sa, 0, sizeof (sa));
  43.  sa.sa_handler = &event_handler;
  44.  sigaction (SIGALRM, &sa, NULL);
  45.  timer.it_value.tv_sec = 0;
  46.  timer.it_value.tv_usec = USECREQ;
  47.  timer.it_interval.tv_sec = 0;
  48.  timer.it_interval.tv_usec = USECREQ;
  49.  setitimer (ITIMER_REAL, &timer, NULL);
  50.  while (1);
  51. }
Success #stdin #stdout 1s 2248KB
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Standard input is empty
stdout
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kernel timer interrupt frequency is approx. 1002 Hz
https://ideone.com/DuEqzt
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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