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| author | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-07-07 08:43:50 +0200 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-07-07 09:07:14 +0200 |
| commit | 641277ecc441c9cd45ad0864abb4f11f34ff4f36 (patch) | |
| tree | 99969fde82418495cffdb566dd9e11ea15e2193b | |
| parent | 00538c672bb50ea4968041344d4234f95f456cd9 (diff) | |
| download | man-pages-641277ecc441c9cd45ad0864abb4f11f34ff4f36.tar.gz | |
sysinfo.2: Rewrite and update various pieces
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
| -rw-r--r-- | man2/sysinfo.2 | 54 |
1 files changed, 35 insertions, 19 deletions
diff --git a/man2/sysinfo.2 b/man2/sysinfo.2 index eea1fae69a..d9f8202c31 100644 --- a/man2/sysinfo.2 +++ b/man2/sysinfo.2 @@ -1,4 +1,9 @@ -.\" Copyright (C) 1993 by Dan Miner (dminer@nyx.cs.du.edu) +.\" 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 @@ -11,15 +16,19 @@ .\" .TH SYSINFO 2 2014-08-19 "Linux" "Linux Programmer's Manual" .SH NAME -sysinfo \- returns information on overall system statistics +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 () -used to return information in the following structure: +returned information in the following structure: .nf .in +4n @@ -31,16 +40,17 @@ struct sysinfo { 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 long freeswap; /* Swap space still available */ unsigned short procs; /* Number of current processes */ char _f[22]; /* Pads structure to 64 bytes */ }; .in .fi .PP -and the sizes were given in bytes. +In the above structure, the sizes of the memory and swap fields +are given in bytes. -Since Linux 2.3.23 (i386), 2.3.48 +Since Linux 2.3.23 (i386) and Linux 2.3.48 (all architectures) the structure is: .nf @@ -53,37 +63,43 @@ struct sysinfo { 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 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 */ + char _f[20\-2*sizeof(long)\-sizeof(int)]; + /* Padding to 64 bytes */ }; .in .fi .PP -and the sizes are given as multiples of \fImem_unit\fP bytes. - -.BR sysinfo () -provides a simple way of getting overall system statistics. -This is more -portable than reading \fI/dev/kmem\fP. +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, zero is returned. +On success, +.BR sysinfo () +returns zero. On error, \-1 is returned, and .I errno -is set appropriately. +is set to indicate the cause of the error. .SH ERRORS .TP .B EFAULT -pointer to \fIstruct\ sysinfo\fP is invalid +.IR info +is not a valid address. .SH VERSIONS -The Linux kernel has a .BR sysinfo () -system call since 0.98.pl6. +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) |