An exclusive cache arrangement

摘要

Cache 25 is configured to receive a memory request from another cache 12 which may be in response to a cache miss. The cache 25 has a memory 50 for storing data and is configured to provide a response to said memory request to the other cache. A cache controller 52 is configured such that the cache memory comprises no allocation for data associated with said memory request so that data is only ever in one of the two caches. No allocation can be achieved by invalidating data lines in the cache 25 when transferring data to the other cache or by not storing data in cache 25 when accessing data from memory via interface 34 to fulfil the request. The caches may be on different dies (2, 4 fig 1) or alternatively may be a first cache and second cache in a cache hierarchy. A prefetch engine 33 may be provided to prefetch data into cache 25.