Editing Cache replacement policies (section)

==== {{Anchor|SLRU}}Segmented LRU (SLRU) ====
An SLRU cache is divided into two segments: probationary and protected. Lines in each segment are ordered from most- to least-recently-accessed. Data from misses is added to the cache at the most-recently-accessed end of the probationary segment. Hits are removed from where they reside and added to the most-recently-accessed end of the protected segment; lines in the protected segment have been accessed at least twice. The protected segment is finite; migration of a line from the probationary segment to the protected segment may force the migration of the LRU line in the protected segment to the most-recently-used end of the probationary segment, giving this line another chance to be accessed before being replaced. The size limit of the protected segment is an SLRU parameter which varies according to [[Input/output|I/O]] workload patterns. When data must be discarded from the cache, lines are obtained from the LRU end of the probationary segment.<ref>Ramakrishna Karedla, J. Spencer Love, and Bradley G. Wherry. Caching Strategies to Improve Disk System Performance. In ''[[Computer (magazine)|Computer]]'', 1994.</ref>