Method for managing a cache hierarchy having a least recently used (lru)

Abstract

A method for managing a cache hierarchy having a fixed total storage capacity is disclosed. The cache hierarchy is logically partitioned to form a least recently used (LRU) global cache and a plurality of LRU destaging local caches. The global cache stores objects of all types and maintains them in LRU order. In contrast, each local cache is bound to objects having a unique data type T(i), where i is indicative of a DataType. Read and write accesses by referencing processors or central processing units (CPU's) are made to the global cache. Data not available in the global cache is staged thereto either from one of the local caches or from external storage. When a cache full condition is reached, placement of the most recently used (MRU) data element to the top of the global cache results in an LRU data element of type T(i) being destaged from the global cache to a corresponding one of the local caches storing type T(i) data. Likewise, when a cache full condition is reached in any one or more of the local caches, the local caches in turn will destage their LRU data elements to external storage. The parameters defining the partitions are externally supplied.