Cleaning Policy
The cleaning policy determines when a modified page should be written out to secondary memory.
- opposite of Fetch Policy
There are 2 common alternatives:
- Demand Cleaning
- Pre-cleaning
Demand cleaning (parallel with Demand Paging)
- A page is written out only when it has been selected for replacement
- Requires two page transfers per page fault
Pre-cleaning (parallel with Prepaging)
- Pages are written out in batches
- Allows bursty long (large block) I/O
- … but write may be unnecessary
Best approach uses Page Buffering.