sysinfo() - Unix, Linux System Call

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. For an example of its use, see intro(2).

RETURN VALUE

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

ERRORS

Tag	Description
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.