Method and apparatus to free up cache memory space with a pseudo least recently used scheme

摘要

A mechanism is provided for identifying data that can be removed from a cache memory by determining a memory region of the cache that is less recently accessed than other memory regions in the cache. A tree data structure is used to store a mapping of storage volume data locations to cache data locations. A counter reflecting recency of access to the cache data location is associated with each entry. The counter is incremented, along with counters associated with keys leading to a node including the entry, with each access to the associated cache memory location, while other counters in each affected node are decremented. Advantages of the tree data structure are used to efficiently locate a cache memory location associated with a counter reflecting a less recently accessed state in order to make that cache memory location available for storage of recently accessed data from the storage volume.