Hacked from top, display overall cpu-usage on FreeBSD..

cpu-usage.c

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/resource.h> 
#include <sys/types.h>
#include <sys/sysctl.h>
static int out[CPUSTATES];
static long cp_old[CPUSTATES];
static long cp_diff[CPUSTATES];
    char *cpustatenames[] = {
	"user", "nice", "system", "interrupt", "idle", NULL
};
long percentages(cnt, out, new, old, diffs)

int cnt;
int *out;
register long *new;
register long *old;
long *diffs;

{
    register int i;
    register long change;
    register long total_change;
    register long *dp;
    long half_total;

    /* initialization */
    total_change = 0;
    dp = diffs;

    /* calculate changes for each state and the overall change */
    for (i = 0; i < cnt; i++)
    {
	if ((change = *new - *old) < 0)
	{
	    /* this only happens when the counter wraps */
	    change = (int)
		((unsigned long)*new-(unsigned long)*old);
	}
	total_change += (*dp++ = change);
	*old++ = *new++;
    }

    /* avoid divide by zero potential */
    if (total_change == 0)
    {
	total_change = 1;
    }

    /* calculate percentages based on overall change, rounding up */
    half_total = total_change / 2l;

    /* Do not divide by 0. Causes Floating point exception */
    if(total_change) {
        for (i = 0; i < cnt; i++)
        {
          *out++ = (int)((*diffs++ * 1000 + half_total) / total_change);
        }
    }

    /* return the total in case the caller wants to use it */
    return(total_change);
}

void cpu_update()
{   

	
	size_t cp_size = sizeof(long) * CPUSTATES*8;
	long *cp_times = malloc(cp_size);

	if (sysctlbyname("kern.cp_time", cp_times, &cp_size, NULL, 0) < 0) {
		perror("sysctlbyname");
		free(cp_times);
	}
    
    percentages(CPUSTATES, out, cp_times, cp_old, cp_diff);
    for(int j=0; j<CPUSTATES;j++)  {
    printf("%s: %.1f%% - ",cpustatenames[j],((float)out[j])/10.00);
    }
    printf("\n");
	free(cp_times);
    
}



int
main(int argc, char *argv[])
{
	for(int i=0;i<100;i++) {
	cpu_update();
	sleep(1);
    }
    
}