git.sur5r.net Git - i3/i3status/blob - src/print_cpu_usage.c

   1 // vim:sw=8:sts=8:ts=8:expandtab
   2 #include <stdlib.h>
   3 #include <limits.h>
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <yajl/yajl_gen.h>
   7 #include <yajl/yajl_version.h>
   8
   9 #if defined(__FreeBSD__) || defined(__OpenBSD__)
  10 #include <sys/param.h>
  11 #include <sys/types.h>
  12 #include <sys/sysctl.h>
  13 #include <sys/dkstat.h>
  14 #endif
  15
  16 #include "i3status.h"
  17
  18 static int prev_total = 0;
  19 static int prev_idle  = 0;
  20
  21 /*
  22  * Reads the CPU utilization from /proc/stat and returns the usage as a
  23  * percentage.
  24  *
  25  */
  26 void print_cpu_usage(yajl_gen json_gen, char *buffer, const char *format) {
  27         const char *walk;
  28         char *outwalk = buffer;
  29         char buf[1024];
  30         int curr_user = 0, curr_nice = 0, curr_system = 0, curr_idle = 0, curr_total;
  31         int diff_idle, diff_total, diff_usage;
  32
  33 #if defined(LINUX)
  34         static char statpath[512];
  35         strcpy(statpath, "/proc/stat");
  36         if (!slurp(statpath, buf, sizeof(buf)) ||
  37             sscanf(buf, "cpu %d %d %d %d", &curr_user, &curr_nice, &curr_system, &curr_idle) != 4)
  38                 goto error;
  39
  40         curr_total = curr_user + curr_nice + curr_system + curr_idle;
  41         diff_idle  = curr_idle - prev_idle;
  42         diff_total = curr_total - prev_total;
  43         diff_usage = (diff_total ? (1000 * (diff_total - diff_idle)/diff_total + 5)/10 : 0);
  44         prev_total = curr_total;
  45         prev_idle  = curr_idle;
  46 #elif defined(__FreeBSD__) || defined(__OpenBSD__)
  47
  48 #if defined(__FreeBSD__)
  49         size_t size;
  50         long cp_time[CPUSTATES];
  51         size = sizeof cp_time;
  52         if (sysctlbyname("kern.cp_time", &cp_time, &size, NULL, 0) < 0)
  53                 goto error;
  54 #else
  55         /* This information is taken from the boot cpu, any other cpus are currently ignored. */
  56         long cp_time[CPUSTATES];
  57         int mib[2];
  58         size_t size = sizeof(cp_time);
  59
  60         mib[0] = CTL_KERN;
  61         mib[1] = KERN_CPTIME;
  62
  63         if (sysctl(mib, 2, cp_time, &size, NULL, 0))
  64                 goto error;
  65 #endif
  66
  67         curr_user = cp_time[CP_USER];
  68         curr_nice = cp_time[CP_NICE];
  69         curr_system = cp_time[CP_SYS];
  70         curr_idle = cp_time[CP_IDLE];
  71         curr_total = curr_user + curr_nice + curr_system + curr_idle;
  72         diff_idle  = curr_idle - prev_idle;
  73         diff_total = curr_total - prev_total;
  74         diff_usage = (diff_total ? (1000 * (diff_total - diff_idle)/diff_total + 5)/10 : 0);
  75         prev_total = curr_total;
  76         prev_idle  = curr_idle;
  77 #else
  78         goto error;
  79 #endif
  80         for (walk = format; *walk != '\0'; walk++) {
  81                 if (*walk != '%') {
  82                         *(outwalk++) = *walk;
  83                         continue;
  84                 }
  85
  86                 if (strncmp(walk+1, "usage", strlen("usage")) == 0) {
  87                         outwalk += sprintf(outwalk, "%02d%%", diff_usage);
  88                         walk += strlen("usage");
  89                 }
  90         }
  91
  92         OUTPUT_FULL_TEXT(buffer);
  93         return;
  94 error:
  95         OUTPUT_FULL_TEXT("cant read cpu usage");
  96         (void)fputs("i3status: Cannot read CPU usage\n", stderr);
  97 }