PERFORMANCE IMPROVEMENT OF A WRITE INSTRUCTION OF A NON-INCLUSIVE HIERARCHICAL CACHE MEMORY UNIT

Described is a data processing system including a processor, a plurality of caches, and main memory, the secondary caches being implemented as being non-inclusive, i.e., the lower order caches not storing a superset of the data stored in the next higher order cache. The non-inclusive cache structure provides increased flexibility in the storage of data. The operation of a write request operation when the target data line is not found in the primary cache. By using the dirty bit associated with each data line, the interaction between the processor and the primary cache can be reduced. By using the invalidity bit associated with each data line, the interaction between the processor and the primary cache can be reduced.