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Linux: implement getloadavg(3) using sysinfo(2)

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Signed-off-by: Cristian Rodríguez <crrodriguez@opensuse.org>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Cristian Rodríguez
2021-08-06 15:17:48 -04:00
committed by Adhemerval Zanella
parent f3c6c19038
commit b5c8a3aa82
1 changed files with 14 additions and 36 deletions
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50
sysdeps/unix/sysv/linux/getloadavg.c
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@ -1,4 +1,4 @@
/* Get system load averages. Linux (/proc/loadavg) version.
/* Get system load averages. Linux version.
Copyright (C) 1999-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
@ -16,53 +16,31 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <locale.h>
#include <stdlib.h>
#include <unistd.h>
#include <not-cancel.h>
#include <array_length.h>
#include <sys/param.h>
#include <sys/sysinfo.h>
/* Put the 1 minute, 5 minute and 15 minute load averages
into the first NELEM elements of LOADAVG.
Return the number written (never more than 3, but may be less than NELEM),
or -1 if an error occurred. */
#define CLAMP(v, lo, hi) MIN (MAX (v, lo), hi)
#define SYSINFO_LOADS_SCALE (1 << SI_LOAD_SHIFT)
int
getloadavg (double loadavg[], int nelem)
{
int fd;
struct sysinfo info;
fd = __open_nocancel ("/proc/loadavg", O_RDONLY);
if (fd < 0)
if (__sysinfo (&info) != 0)
return -1;
else
{
char buf[65], *p;
ssize_t nread;
int i;
nread = __read_nocancel (fd, buf, sizeof buf - 1);
__close_nocancel_nostatus (fd);
if (nread <= 0)
return -1;
buf[nread - 1] = '\0';
nelem = CLAMP (nelem, 0, array_length (info.loads));
if (nelem > 3)
nelem = 3;
p = buf;
for (i = 0; i < nelem; ++i)
{
char *endp;
loadavg[i] = __strtod_l (p, &endp, _nl_C_locobj_ptr);
if (endp == p)
/* This should not happen. The format of /proc/loadavg
must have changed. Don't return with what we have,
signal an error. */
return -1;
p = endp;
}
for (int i = 0; i < nelem; i++)
loadavg[i] = (double) info.loads[i] / SYSINFO_LOADS_SCALE;
return i;
}
return nelem;
}