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libbb: factor out common code from mpstat/iostat

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko
2010-08-16 02:49:21 +02:00
parent a4160e15ec
commit c9b9750a0e
5 changed files with 56 additions and 66 deletions
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3
libbb/Kbuild.src
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@ -157,6 +157,9 @@ lib-$(CONFIG_MOUNT) += find_mount_point.o
lib-$(CONFIG_HWCLOCK) += rtc.o
lib-$(CONFIG_RTCWAKE) += rtc.o
lib-$(CONFIG_IOSTAT) += get_cpu_count.o
lib-$(CONFIG_MPSTAT) += get_cpu_count.o
# We shouldn't build xregcomp.c if we don't need it - this ensures we don't
# require regex.h to be in the include dir even if we don't need it thereby
# allowing us to build busybox even if uclibc regex support is disabled.

47
libbb/get_cpu_count.c Normal file
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@ -0,0 +1,47 @@
/* vi: set sw=4 ts=4: */
/*
* Factored out of mpstat/iostat.
*
* Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
*
* Licensed under GPLv2, see file License in this tarball for details.
*/
#include "libbb.h"
/* Does str start with "cpu"? */
int FAST_FUNC starts_with_cpu(const char *str)
{
return ((str[0] - 'c') | (str[1] - 'p') | (str[2] - 'u')) == 0;
}
/*
* Get number of processors. Uses /proc/stat.
* Return value 0 means one CPU and non SMP kernel.
* Otherwise N means N processor(s) and SMP kernel.
*/
unsigned FAST_FUNC get_cpu_count(void)
{
FILE *fp;
char line[256];
int proc_nr = -1;
fp = xfopen_for_read("/proc/stat");
while (fgets(line, sizeof(line), fp)) {
if (!starts_with_cpu(line)) {
if (proc_nr >= 0)
break; /* we are past "cpuN..." lines */
continue;
}
if (line[3] != ' ') { /* "cpuN" */
int num_proc;
if (sscanf(line + 3, "%u", &num_proc) == 1
&& num_proc > proc_nr
) {
proc_nr = num_proc;
}
}
}
fclose(fp);
return proc_nr + 1;
}