MRU

MRU stands for Most Recently Used. It is a cache replacement policy used to decide which item to evict when a cache is full. Under MRU, the item that was most recently accessed is removed to make room for a new one, in contrast to the more common Least Recently Used (LRU) policy, which evicts the item that has been unused for the longest time.

Implementation typically involves tracking access order for cached items. This can be done with simple structures that maintain the most recently used item, or with broader ordering to support more complex eviction decisions. The goal is to identify the candidate to remove when space is needed, based on recent access history.

MRU can be advantageous for workloads where recently used data is unlikely to be needed again soon, such as certain sequential scans or structured access patterns. In these cases evicting the most recently used item can prevent retaining data that is soon to be discarded, while older items that may still be useful are kept longer. However, MRU is not generally suitable for workloads with strong temporal locality, where recently used data is often reused, a pattern that LRU tends to exploit.

MRU is one of several cache replacement strategies, alongside LRU, LFU, FIFO, and clock-based approaches. Its use tends to be niche and workload-dependent, reflecting trade-offs between reuse patterns, eviction cost, and cache management complexity.