man2/sysinfo.2

   1 .\" Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com>
   2 .\" Based on an earlier version of the page where a few pieces were
   3 .\" copyright (C) 1993 by Dan Miner (dminer@nyx.cs.du.edu) and subsequently
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   5 .\" The structure definitions are taken more or less straight from the kernel
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  31 .\" Modified Sat Jul 24 12:35:12 1993 by Rik Faith <faith@cs.unc.edu>
  32 .\" Modified Tue Oct 22 22:29:51 1996 by Eric S. Raymond <esr@thyrsus.com>
  33 .\" Modified Mon Aug 25 16:06:11 1997 by Nicolás Lichtmaier <nick@debian.org>
  34 .\"
  35 .TH SYSINFO 2 2017-09-15 "Linux" "Linux Programmer's Manual"
  36 .SH NAME
  37 sysinfo \- return system information
  38 .SH SYNOPSIS
  39 .B #include <sys/sysinfo.h>
  40 .PP
  41 .BI "int sysinfo(struct sysinfo *" info );
  42 .SH DESCRIPTION
  43 .BR sysinfo ()
  44 returns certain statistics on memory and swap usage,
  45 as well as the load average.
  46 .PP
  47 Until Linux 2.3.16,
  48 .BR sysinfo ()
  49 returned information in the following structure:
  50 .PP
  51 .in +4n
  52 .EX
  53 struct sysinfo {
  54     long uptime;             /* Seconds since boot */
  55     unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
  56     unsigned long totalram;  /* Total usable main memory size */
  57     unsigned long freeram;   /* Available memory size */
  58     unsigned long sharedram; /* Amount of shared memory */
  59     unsigned long bufferram; /* Memory used by buffers */
  60     unsigned long totalswap; /* Total swap space size */
  61     unsigned long freeswap;  /* Swap space still available */
  62     unsigned short procs;    /* Number of current processes */
  63     char _f[22];             /* Pads structure to 64 bytes */
  64 };
  65 .EE
  66 .in
  67 .PP
  68 In the above structure, the sizes of the memory and swap fields
  69 are given in bytes.
  70 .PP
  71 Since Linux 2.3.23 (i386) and Linux 2.3.48
  72 (all architectures) the structure is:
  73 .PP
  74 .in +4n
  75 .EX
  76 struct sysinfo {
  77     long uptime;             /* Seconds since boot */
  78     unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
  79     unsigned long totalram;  /* Total usable main memory size */
  80     unsigned long freeram;   /* Available memory size */
  81     unsigned long sharedram; /* Amount of shared memory */
  82     unsigned long bufferram; /* Memory used by buffers */
  83     unsigned long totalswap; /* Total swap space size */
  84     unsigned long freeswap;  /* Swap space still available */
  85     unsigned short procs;    /* Number of current processes */
  86     unsigned long totalhigh; /* Total high memory size */
  87     unsigned long freehigh;  /* Available high memory size */
  88     unsigned int mem_unit;   /* Memory unit size in bytes */
  89     char _f[20\-2*sizeof(long)\-sizeof(int)];
  90                              /* Padding to 64 bytes */
  91 };
  92 .EE
  93 .in
  94 .PP
  95 In the above structure,
  96 sizes of the memory and swap fields are given as multiples of
  97 .I mem_unit
  98 bytes.
  99 .SH RETURN VALUE
 100 On success,
 101 .BR sysinfo ()
 102 returns zero.
 103 On error, \-1 is returned, and
 104 .I errno
 105 is set to indicate the cause of the error.
 106 .SH ERRORS
 107 .TP
 108 .B EFAULT
 109 .IR info
 110 is not a valid address.
 111 .SH VERSIONS
 112 .BR sysinfo ()
 113 first appeared in Linux 0.98.pl6.
 114 .SH CONFORMING TO
 115 This function is Linux-specific, and should not be used in programs
 116 intended to be portable.
 117 .SH NOTES
 118 All of the information provided by this system call is also available via
 119 .IR /proc/meminfo
 120 and
 121 .IR /proc/loadavg .
 122 .SH SEE ALSO
 123 .BR proc (5)