blob: ab468afdfca9e28814e7111ad3dc82e91367701d
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Factored out of mpstat/iostat. |
4 | * |
5 | * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com> |
6 | * |
7 | * Licensed under GPLv2, see file LICENSE in this source tree. |
8 | */ |
9 | #include "libbb.h" |
10 | |
11 | /* Does str start with "cpu"? */ |
12 | int 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 | */ |
22 | unsigned 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 | } |
48 |