Name
swapon, swapoff — start/stop swapping to
file/device
Synopsis
int
swapon( |
const char * |
path, |
| |
int |
swapflags); |
int
swapoff( |
const char * |
path); |
DESCRIPTION
swapon() sets the swap area
to the file or block device specified by path. swapoff() stops swapping to the file or
block device specified by path.
swapon() takes a swapflags argument. If
swapflags has the
SWAP_FLAG_PREFER bit turned on,
the new swap area will have a higher priority than default.
The priority is encoded within swapflags as:
These functions may only be used by a privileged process
(one having the CAP_SYS_ADMIN
capability).
Priority
Each swap area has a priority, either high or low. The
default priority is low. Within the low-priority areas,
newer areas are even lower priority than older areas.
All priorities set with swapflags are high-priority,
higher than default. They may have any non-negative value
chosen by the caller. Higher numbers mean higher
priority.
Swap pages are allocated from areas in priority order,
highest priority first. For areas with different
priorities, a higher-priority area is exhausted before
using a lower-priority area. If two or more areas have the
same priority, and it is the highest priority available,
pages are allocated on a round-robin basis between
them.
As of Linux 1.3.6, the kernel usually follows these
rules, but there are exceptions.
RETURN VALUE
On success, zero is returned. On error, −1 is
returned, and errno is set
appropriately.
ERRORS
- EBUSY
-
(for swapon()) The
specified path
is already being used as a swap area.
- EINVAL
-
The file path exists, but refers
neither to a regular file nor to a block device; or,
for swapon(), the
indicated path does not contain a valid swap signature;
or, for swapoff(),
path is not
currently a swap area.
- ENFILE
-
The system limit on the total number of open files
has been reached.
- ENOENT
-
The file path does not exist.
- ENOMEM
-
The system has insufficient memory to start
swapping.
- EPERM
-
The caller does not have the CAP_SYS_ADMIN capability, or all
MAX_SWAPFILES (earlier 8;
32 since Linux 2.4.10) are in use.
CONFORMING TO
These functions are Linux specific and should not be used
in programs intended to be portable. The second swapflags argument was
introduced in Linux 1.3.2.
NOTES
The partition or path must be prepared with mkswap(8).
SEE ALSO
mkswap(8), swapoff(8), swapon(8)
Copyright (c) 1992 Drew Eckhardt (drew@cs.colorado.edu), March 28, 1992
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date. The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein. The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.
Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
Modified by Michael Haardt <michael@moria.de>
Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
Modified 1995-07-22 by Michael Chastain <mec@duracef.shout.net>
Modified 1995-07-23 by aeb
Modified 1996-10-22 by Eric S. Raymond <esr@thyrsus.com>
Modified 1998-09-08 by aeb
Modified 2004-06-17 by Michael Kerrisk <mtk-manpages@gmx.net>
Modified 2004-10-10 by aeb
2004-12-14 mtk, Anand Kumria: added new errors
|
