swapon(2) -- Linux man page
NAMEswapon, swapoff - start/stop swapping to file/device
#include <asm/page.h> /* to find PAGE_SIZE */
DESCRIPTIONswapon 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.
bit turned on, the new swap area will have a higher priority than default.
The priority is encoded as:
(prio << SWAP_FLAG_PRIO_SHIFT) & SWAP_FLAG_PRIO_MASK
PRIORITYEach 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.
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORSMany other errors can occur if path is not valid.
- The user is not the super-user, or more than MAX_SWAPFILES (defined to be 8 in Linux 1.3.6) are in use.
- is returned if path exists, but is neither a regular path nor a block device.
- is returned if path does not exist.
- is returned if there is insufficient memory to start swapping.
CONFORMING TOThese 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.
NOTESThe partition or path must be prepared with mkswap(8).
SEE ALSOmkswap(8), swapon(8), swapoff(8)