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/.

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 */
};