PPT Slide
Page Replacement Algorithms
- FIFO: Replace the page that has been in memory the longest.
- Theory is that oldest page won’t be used in near future.
- Bad theory :) (Figure 12.2).
- Least-Recently Used (LRU): Replace the page that has not been accessed in the longest time.
- Predict the recent future from the recent past.
- Good theory & best global paging algorithm (30 - 40% of Optimal).
- Expensive to record timestamps, though (Figure 12.4).
- Easier to approximate LRU via software & hardware.