sysinfo(2) — Linux manual pages

Linux manual pages	Section 2

Name

sysinfo — returns information on overall system statistics

Synopsis

#include <sys/sysinfo.h>

int sysinfo( struct sysinfo *info);

DESCRIPTION

Until Linux 2.3.16, sysinfo() used to return information in the following structure:

struct sysinfo {

long uptime;
/* Seconds since boot */

unsigned long loads[3];
/* 1, 5, and 15 minute load averages */

unsigned long totalram;
/* Total usable main memory size */

unsigned long freeram;
/* Available memory size */

unsigned long sharedram;
/* Amount of shared memory */

unsigned long bufferram;
/* Memory used by buffers */

unsigned long totalswap;
/* Total swap space size */

unsigned long freeswap;
/* swap space still available */

unsigned short procs;
/* Number of current processes */

char _f[22];
/* Pads structure to 64 bytes */

};

and the sizes were given in bytes.

Since Linux 2.3.23 (i386), 2.3.48 (all architectures) the structure is:

struct sysinfo {
    long uptime;             /* Seconds since boot */
    unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
    unsigned long totalram;  /* Total usable main memory size */
    unsigned long freeram;   /* Available memory size */
    unsigned long sharedram; /* Amount of shared memory */
    unsigned long bufferram; /* Memory used by buffers */
    unsigned long totalswap; /* Total swap space size */
    unsigned long freeswap;  /* swap space still available */
    unsigned short procs;    /* Number of current processes */
    unsigned long totalhigh; /* Total high memory size */
    unsigned long freehigh;  /* Available high memory size */
    unsigned int mem_unit;   /* Memory unit size in bytes */
    char _f[20−2*sizeof(long)−sizeof(int)]; /* Padding for libc5 */
};

and the sizes are given as multiples of mem_unit bytes.

sysinfo() provides a simple way of getting overall system statistics. This is more portable than reading /dev/kmem.

RETURN VALUE

On success, zero is returned. On error, −1 is returned, and errno is set appropriately.

ERRORS

EFAULT: pointer to struct sysinfo is invalid

CONFORMING TO

This function is Linux-specific, and should not be used in programs intended to be portable.

The Linux kernel has a sysinfo() system call since 0.98.pl6. Linux libc contains a sysinfo() routine since 5.3.5, and glibc has one since 1.90.

COLOPHON

This page is part of release 3.33 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://man7.org/linux/man-pages/.

Copyright (C) 1993 by Dan Miner (dminernyx.cs.du.edu)

Permission is granted to freely distribute or modify this file
for the purpose of improving Linux or its documentation efforts.
If you modify this file, please put a date stamp and HOW you
changed this file. Thanks. -DM

Modified Sat Jul 24 12:35:12 1993 by Rik Faith <faithcs.unc.edu>
Modified Tue Oct 22 22:29:51 1996 by Eric S. Raymond <esrthyrsus.com>
Modified Mon Aug 25 16:06:11 1997 by Nicolás Lichtmaier <nickdebian.org>

struct	sysinfo {
	long	`uptime`;	/* Seconds since boot */
	unsigned long	`loads`[3];	/* 1, 5, and 15 minute load averages */
	unsigned long	`totalram`;	/* Total usable main memory size */
	unsigned long	`freeram`;	/* Available memory size */
	unsigned long	`sharedram`;	/* Amount of shared memory */
	unsigned long	`bufferram`;	/* Memory used by buffers */
	unsigned long	`totalswap`;	/* Total swap space size */
	unsigned long	`freeswap`;	/* swap space still available */
	unsigned short	`procs`;	/* Number of current processes */
	char	`_f`[22];	/* Pads structure to 64 bytes */
};