Patent attributes
In one embodiment, a node for a multi-node computer system comprises a coherence directory and a coherence controller. The coherence directory comprises a plurality of entries, wherein each entry corresponds to a respective coherence unit and stores a state identifying which nodes in the computer system are storing a copy of the coherence unit and further identifying a coherence state of the coherence unit according to a coherence protocol implemented in the computer system. Coupled to the directory and coupled to receive a first request for a requested coherence unit having a first entry in the coherence directory, the coherence controller is coupled to receive a second request for the requested coherence unit. The coherence controller is configured to selectively initiate coherence activity for the second request, if coherence activity for the first request is not yet complete, dependent on a type of the second request.
