Buffer Replacement Policy
Frame is chosen for replacement by a replacement policy:
- Least-recently-used (LRU), Clock, MRU, etc.
Policy can have big impact on # of I/O’s; depends on the access pattern.
Sequential flooding: Nasty situation caused by LRU + repeated sequential scans.
- # buffer frames < # pages in file means each page request causes an I/O. MRU much better in this situation (but not in all situations, of course).