.\" Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
.\" Based on an earlier version of the page where a few pieces were
.\" copyright (C) 1993 by Dan Miner (dminer@nyx.cs.du.edu) and subsequently
.\" others (see old changelog below).
.\" The structure definitions are taken more or less straight from the kernel
.\" source files.
.\"
.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE)
.\"  Permission is granted to freely distribute or modify this file
.\"  for the purpose of improving Linux or its documentation efforts.
.\" %%%LICENSE_END
.\"
.\" Modified Sat Jul 24 12:35:12 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Tue Oct 22 22:29:51 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified Mon Aug 25 16:06:11 1997 by Nicolás Lichtmaier <nick@debian.org>
.\"
.TH SYSINFO 2 2014-08-19 "Linux" "Linux Programmer's Manual"
.SH NAME
sysinfo \- return system information
.SH SYNOPSIS
.B #include <sys/sysinfo.h>
.sp
.BI "int sysinfo(struct sysinfo *" info );
.SH DESCRIPTION
.BR sysinfo ()
returns certain statistics on memory and swap usage,
as well as the load average.

Until Linux 2.3.16,
.BR sysinfo ()
returned information in the following structure:

.nf
.in +4n
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 */
};
.in
.fi
.PP
In the above structure, the sizes of the memory and swap fields
are given in bytes.

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

.nf
.in +4n
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 to 64 bytes */
};
.in
.fi
.PP
In the above structure,
sizes of the memory and swap fields are given as multiples of
.I mem_unit
bytes.
.SH RETURN VALUE
On success,
.BR sysinfo ()
returns zero.
On error, \-1 is returned, and
.I errno
is set to indicate the cause of the error.
.SH ERRORS
.TP
.B EFAULT
.IR info
is not a valid address.
.SH VERSIONS
.BR sysinfo ()
first appeared in Linux 0.98.pl6.
.SH CONFORMING TO
This function is Linux-specific, and should not be used in programs
intended to be portable.
.SH NOTES
All of the information provided by this system call is also available via
.IR /proc/meminfo
and
.IR /proc/loadavg .
.SH SEE ALSO
.BR proc (5)