Early freeing of a snoop machine of a data processing system prior to completion of snoop processing for an interconnect operation

摘要

A multiprocessor data processing system includes multiple vertical cache hierarchies supporting a plurality of processor cores, a system memory, and an interconnect fabric. In response to a first cache memory snooping on the interconnect fabric a request of an interconnect operation of a second cache memory, the first cache memory allocates a snoop machine to service the request. Responsive to the snoop machine completing its processing of the request and prior to the first cache memory receiving a systemwide coherence response of the interconnect operation, the first cache memory allocates an entry in a data structure to handle completion of processing for the interconnection operation and deallocates the snoop machine. The entry of the data structure protects transfer of coherence ownership of a target cache line from the first cache memory to the second cache memory during a protection window extending at least until the systemwide coherence response is received.