1756894282qqcom • 2021-01-01 21:38:51

First in first out (FIFO)
Idea: select the page with the longest residence time in memory for replacement
Implementation: maintain a link list of all the logical pages in memory. The elements of the link list are sorted according to the time of staying in memory. The chain head is the longest and the chain tail is the shortest. In case of missing pages, select the front page of the chain to replace, and add the new page to the end of the chain
Features: simple implementation; poor performance, the page may be frequently visited
The detailed replacement process can be understood through the figure below. There are 5 missing pages in the figure PostVer 0

1756894282qqcom • 2021-01-01 21:39:24

Least recently used (LRU)
Idea: select the pages that have not been referenced for a long time for replacement, because if some pages have not been accessed for a long time, they may not be accessed for a long time in the future
Implementation: when the page is missing, calculate the last access time of each logical page in memory, and select the page that last used to the current longest time
Features: it is possible to achieve the optimal effect, and the cost of maintaining such an access list is relatively large PostVer 0