[PATCH 1/2] Linux: implement getloadavg(3) using sysinfo(2)
Cristian Rodríguez
crrodriguez@opensuse.org
Thu Aug 12 18:51:41 GMT 2021
ping
On Fri, Aug 6, 2021 at 3:18 PM Cristian Rodríguez
<crrodriguez@opensuse.org> wrote:
>
> Signed-off-by: Cristian Rodríguez <crrodriguez@opensuse.org>
> ---
> sysdeps/unix/sysv/linux/getloadavg.c | 50 ++++++++--------------------
> 1 file changed, 14 insertions(+), 36 deletions(-)
>
> diff --git a/sysdeps/unix/sysv/linux/getloadavg.c b/sysdeps/unix/sysv/linux/getloadavg.c
> index e50cc396e7..3ea7fd02b7 100644
> --- a/sysdeps/unix/sysv/linux/getloadavg.c
> +++ b/sysdeps/unix/sysv/linux/getloadavg.c
> @@ -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, (int)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;
> }
> --
> 2.32.0
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