blob: edb7e6d372c75fe6142eceff2212c434a0a15c6b [file] [log] [blame]
Denys Vlasenkoc9b97502010-08-16 02:49:21 +02001/* vi: set sw=4 ts=4: */
2/*
3 * Factored out of mpstat/iostat.
4 *
5 * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
6 *
Denys Vlasenko9768a822010-08-16 03:04:14 +02007 * Licensed under GPLv2, see file LICENSE in this tarball for details.
Denys Vlasenkoc9b97502010-08-16 02:49:21 +02008 */
9#include "libbb.h"
10
11/* Does str start with "cpu"? */
12int FAST_FUNC starts_with_cpu(const char *str)
13{
14 return ((str[0] - 'c') | (str[1] - 'p') | (str[2] - 'u')) == 0;
15}
16
17/*
18 * Get number of processors. Uses /proc/stat.
19 * Return value 0 means one CPU and non SMP kernel.
20 * Otherwise N means N processor(s) and SMP kernel.
21 */
22unsigned FAST_FUNC get_cpu_count(void)
23{
24 FILE *fp;
25 char line[256];
26 int proc_nr = -1;
27
28 fp = xfopen_for_read("/proc/stat");
29 while (fgets(line, sizeof(line), fp)) {
30 if (!starts_with_cpu(line)) {
31 if (proc_nr >= 0)
32 break; /* we are past "cpuN..." lines */
33 continue;
34 }
35 if (line[3] != ' ') { /* "cpuN" */
36 int num_proc;
37 if (sscanf(line + 3, "%u", &num_proc) == 1
38 && num_proc > proc_nr
39 ) {
40 proc_nr = num_proc;
41 }
42 }
43 }
44
45 fclose(fp);
46 return proc_nr + 1;
47}