Abstract: A data processing system including multiple processors 6, 8, 10, 12 each with a local cache memory 14, 16, 18, 20 share a main memory 24 under control of a coherency controller 22. Store requests from a store requester which are to be serviced by data received from the main memory 24 trigger the coherency controller 22 to return exclusive rights to access the data to the store requester before the corresponding data is returned from the main memory 24. The store requester uses possession of the exclusive rights to access the data to permit further processing with an ordering constraint relative to the store request to proceed even though the store request has yet to be finished. The ordering constraint may be, for example, a fence instruction. The store requester in possession of the exclusive rights to access the data values ensures that the store request is finished and its results observed by any instruction as required by the ordering constraint it has released early.

Abstract: A data processing system including multiple processors 6, 8, 10, 12 each with a local cache memory 14, 16, 18, 20 share a main memory 24 under control of a coherency controller 22. Store requests from a store requester which are to be serviced by data received from the main memory 24 trigger the coherency controller 22 to return exclusive rights to access the data to the store requester before the corresponding data is returned from the main memory 24. The store requester uses possession of the exclusive rights to access the data to permit further processing with an ordering constraint relative to the store request to proceed even though the store request has yet to be finished. The ordering constraint may be, for example, a fence instruction. The store requester in possession of the exclusive rights to access the data values ensures that the store request is finished and its results observed by any instruction as required by the ordering constraint it has released early.