Method and apparatus for a data-less write operation within a cache memory hierarchy for a data processing system

摘要

A method and apparatus for casing out data within a cache memory hierarchy for a data processing system is disclosed. The data processing system has multiple processing units, each of the processing units having a multi-level cache memory hierarchy. The cache memory hierarchy includes a first cache and a second cache at a same cache level. Furthermore, the first cache and the second cache share a lower-level cache. In response to a castout write request from the first cache to the lower-level cache, the second cache aborts the data transfer for the castout write request if the second cache already has a copy of data of the castout write request. The coherency state of both the first and second caches are then updated.