CPU 사용율 구하기(1)

참조 : directfb예제중 df_cpuload.c 를 이용.
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <gtk/gtk.h>

#define SET_IF_DESIRED(x,y) do{  if(x) *(x) = (y); }while(0)
#define JT unsigned long

static void four_cpu_numbers(int *uret, int *nret, int *sret, int *iret);
static int get_load();
void* cpu_load(int t);

GThread *adc_insert_thrs;
GError *adc_error;

static void four_cpu_numbers(int *uret, int *nret, int *sret, int *iret)
{
     int       tmp_u, tmp_n, tmp_s, tmp_i;
     static JT old_u, old_n, old_s, old_i, old_wa, old_hi, old_si;
     JT        new_u, new_n, new_s, new_i, new_wa = 0, new_hi = 0, new_si = 0;
     JT        ticks_past; /* avoid div-by-0 by not calling too often :-( */
     char      dummy[16];
     FILE     *stat;

     stat = fopen ("/proc/stat", "r");
     if (!stat)
          return;

     if (fscanf (stat, "%s %lu %lu %lu %lu %lu %lu %lu", dummy,
                 &new_u, &new_n, &new_s, &new_i, &new_wa, &new_hi, &new_si) < 5)
     {
          fclose (stat);
          return;
     }

     fclose (stat);

     ticks_past = ((new_u + new_n + new_s + new_i + new_wa + new_hi + new_si) -
                   (old_u + old_n + old_s + old_i + old_wa + old_hi + old_si));
     if (ticks_past) {
          tmp_u = ((new_u - old_u) << 16) / ticks_past;
          tmp_n = ((new_n - old_n) << 16) / ticks_past;
          tmp_s = ((new_s - old_s) << 16) / ticks_past;
          tmp_i = ((new_i - old_i) << 16) / ticks_past;
     }
     else {
          tmp_u = 0;
          tmp_n = 0;
          tmp_s = 0;
          tmp_i = 0;
     }

     SET_IF_DESIRED(uret, tmp_u);
     SET_IF_DESIRED(nret, tmp_n);
     SET_IF_DESIRED(sret, tmp_s);
     SET_IF_DESIRED(iret, tmp_i);

     old_u  = new_u;
     old_n  = new_n;
     old_s  = new_s;
     old_i  = new_i;
     old_wa = new_wa;
     old_hi = new_hi;
     old_si = new_si;
}
#undef JT

static int
get_load()
{
     static int old_load = 0;

     int u = 0, n = 0, s = 0, i, load;

     four_cpu_numbers( &u, &n, &s, &i );

     //load = u + n + s;
     load = u + n + s + i;

     //old_load = (load + load + load + old_load) >> 2;
     old_load = ((u+n+s)*100) / (load);

     //return old_load >> 10;
     return old_load;
}

void* cpu_load(int t)
{
 int load;
 while(1){
  usleep(100000);
  load = get_load();
  printf("cpu load = %d\n",load);
 }
 
 return (void*)0;
}

int main(int argc, char** argv)
{
 int load;
 g_thread_init(NULL);
 adc_insert_thrs = g_thread_create((GThreadFunc)cpu_load,0,TRUE,&adc_error);
 
 g_thread_join(adc_insert_thrs );
 /*
 while(1){
  usleep(100000);
  load = get_load();
  printf("cpu load = %d\n",load);
 }
 //*/
 
  return 0;
}