Patent ID: 7099913

Claim:
A distributed multiprocessing computer system, comprising: a plurality of processor nodes each coupled to an associated memory module, wherein each memory module may store data that is shared between said processor nodes; a Home processor node that includes a data block and a coherence directory for said data block in an associated memory module; an Owner processor node that includes a copy of said data block in a memory module associated with the Owner processor node, said copy of said data block residing exclusively in said memory module; a Requestor processor node that encounters a read or write miss of said data block and requests said data block from the Home processor node; and wherein said Home processor node receives the request for the data block from the Requestor processor node, forwards the request to the Owner processor node for the data block and performs a speculative write of the next directory state to the coherence directory for the data block without waiting for the Owner processor node to respond to the request.