swap definition operating system
To move a program from fast-access memory to a slow-access memory ("swap out"), or vice versa ("swap in"). The term often refers specifically to the use of a hard disk
(or a swap file
) as virtual memory
or "swap space".
When a program is to be executed, possibly as determined by a scheduler
, it is swapped into core
for processing; when it can no longer continue executing for some reason, or the scheduler decides its time slice
has expired, it is swapped out again.
This contrasts with "paging" systems in which only parts of a program's memory is transfered.