Determines when a page should be brought into main memory. Two common policies:
- Demand paging only brings pages into main memory when a reference is made to a location on the page (paging on demand only).
- many page faults when a process is started but should decrease as more pages are brought in.
- Prepaging brings in more pages than needed.
- It is more efficient to bring in pages that reside contiguously on the disk.
- efficiency not definitely established: the extra pages brought in are “often” not referenced.