Patent ID: 8139592

Claim:
A data processing system, comprising: a plurality of identical processing units coupled by a plurality of communication links for point-to-point communication such that at least some of the communication between multiple different ones of said processing units is transmitted via at least one intermediate processing unit among the plurality of processing units, wherein said communication includes operations each having a request and a combined response representing a system response to the request; wherein said at least one intermediate processing unit among said plurality of processing units includes: at least one processor core that executes instructions; one or more masters that initiate first operations; a snooper that receives second operations initiated by one other of said plurality of processing units; a physical queue that stores master tags of first operations initiated by the one or more masters within that processing unit; and a ticketing mechanism that assigns to a second operation observed at the intermediate processing unit a ticket number indicating an order of observation with respect to other second operations observed by the intermediate processing unit, wherein said ticketing mechanism provides the ticket number assigned to an operation to the snooper for processing with a combined response of the operation; wherein said ticketing mechanism has a plurality of operation tracking structures each tracking operations received from a respective one of a plurality of routes along said communication links.