idlestat.c

   1 #define _GNU_SOURCE
   2 #include <err.h>
   3 #include <time.h>
   4 #include <stdio.h>
   5 #include <fcntl.h>
   6 #include <alloca.h>
   7 #include <unistd.h>
   8 #include <stdlib.h>
   9 #include <sys/time.h>
  10 #include <sys/sysinfo.h>
  11
  12 static double now (void)
  13 {
  14     struct timeval tv;
  15
  16     if (gettimeofday (&tv, NULL))
  17         err (1, "gettimeofday");
  18     return tv.tv_sec + tv.tv_usec * 1e-6;
  19 }
  20
  21 static void idlenow (int fd, int nprocs, double *p)
  22 {
  23     struct timeval tv;
  24     size_t n = nprocs * sizeof (tv);
  25     ssize_t m;
  26     struct timeval *buf;
  27     int i;
  28
  29     buf = alloca (n);
  30     if (!buf) errx (1, "alloca failed");
  31
  32     m = read (fd, buf, n);
  33     if (n - m) err (1, "read [n=%zu, m=%zi]", n, m);
  34
  35     for (i = 0; i < nprocs; ++i)
  36         p[i] = buf[i].tv_sec + buf[i].tv_usec * 1e-6;
  37 }
  38
  39 int main (int argc, char **argv)
  40 {
  41     int fd;
  42     int nprocs;
  43     double *idle;
  44     int flip = 0;
  45     double *curr, *prev;
  46
  47     (void) argc;
  48     (void) argv;
  49
  50     nprocs = get_nprocs ();
  51     if (nprocs <= 0) errx (1, "get_nprocs returned %d", nprocs);
  52
  53     idle = malloc (2 * nprocs * sizeof (idle[0]));
  54     if (!idle) errx (1, "malloc %zu failed", 2 * nprocs * sizeof (idle[0]));
  55
  56     fd = open ("/dev/itc", O_RDONLY);
  57     if (fd < 0) err (1, "open /dev/itc");
  58
  59     idlenow (fd, nprocs, idle);
  60
  61     flip = 0;
  62     curr = &idle[nprocs];
  63     prev = idle;
  64
  65     for (;;) {
  66         int i;
  67         double s, e, d, *t;
  68
  69         s = now ();
  70         idlenow (fd, nprocs, prev);
  71         sleep (1);
  72         e = now ();
  73         d = e - s;
  74         idlenow (fd, nprocs, curr);
  75
  76         for (i = 0; i < nprocs; ++i) {
  77             double di = curr[i] - prev[i];
  78
  79             printf ("cpu%d load - %.2f%%\n", i, 100.0 * (1.0 - di / d));
  80         }
  81
  82         t = curr;
  83         curr = prev;
  84         prev = t;
  85     }
  86 }