Editing Memory paging (section)

== Page replacement techniques ==
{{Main|Page replacement algorithm}}
=== Free page queue, stealing, and reclamation ===
The free page queue is a list of page frames that are available for assignment. Preventing this queue from being empty minimizes the computing necessary to service a page fault. Some operating systems periodically look for pages that have not been recently referenced and then free the page frame and add it to the free page queue, a process known as "page stealing". Some operating systems{{efn|For example, [[MVS]] (Multiple Virtual Storage).}} support ''page reclamation''; if a program commits a page fault by referencing a page that was stolen, the operating system detects this and restores the page frame without having to read the contents back into RAM.

=== Pre-cleaning ===
The operating system may periodically pre-clean dirty pages: write modified pages back to secondary storage{{efn|name=secondary}} even though they might be further modified. This minimizes the amount of cleaning needed to obtain new page frames at the moment a new program starts or a new data file is opened, and improves responsiveness. (Unix operating systems periodically use [[sync (Unix)|sync]] to pre-clean all dirty pages; Windows operating systems use "modified page writer" threads.)

Some systems allow application hints; the application may request that a page be cleared or paged out and continue without delay.