Most-recently used algorithm, Operating System

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Evicting the most-recently used (MRU) page does very well on LRU's worst case. In general, however, MRU is a bad idea, since many programs exhibit temporal locality in their memory accesses, and MRU is effectively assuming that memory accesses will not exhibit locality.Another possibility is First-In, First-Out, or FIFO. At ?rst, this seems like it would be competitive with LRU, but it is not, since it also ignores temporal locality. For example, with a cache size of three, and the access pattern ABCAD, A would be evicted when D is loaded into the cache, which generally is not a good idea. (FIFO also has an unusual property called Belady's Anomaly in which for contrived examples, means that adding more memory to a system can cause more paging. So adding more physical memory to a computer using FIFO replacement could in theory make it slower. This cannot happen with LRU replacement.


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