A preemptive write back controller is described. The present invention is well suited for a cache, main memory, or other temporarily private data storage that implements a write back strategy. The preemptive write back controller includes a list of the lines, pages, words, memory locations, or sets of memory locations potentially requiring a write back (i.e., those which previously experienced a write operation into them) in a write back cache, write back main memory, or other write back temporarily private data storage. Thus, the preemptive write back controller can initiate or force a preemptive cleaning of these lines, pages, words, memory locations, or sets of memory locations.