Early coherency indication for return data in shared memory architecture

A circuit arrangement, comprising:

• a communications interface configured to communicate return data over a communications link in response to a request;
• a coherency directory configured to store coherency information that identifies a source of the return data for the request;
• and
• control logic coupled to the communications interface and the coherency directory and configured to enable the communications interface to communicate return data over the communications link when the return data is received by the communications interface from a source, wherein the control logic is configured to access the coherency directory in response to the request and in connection with enabling the communications interface to communicate the return data over the communications link, and wherein the control logic is further configured to update the coherency directory independent of enabling the communications interface to communicate the return data over the communications link.

A method of processing a request for data in a data processing system of the type including a communications interface configured to communicate return data over a communications link in response to the request, the method comprising, in response to the request:

• accessing coherency information stored in a coherency directory to identify a source of return data for the request;
• updating the coherency directory based upon the request;
• and
• prior to updating the coherency directory, indicating to the communications interface that the return data can be used by the communications interface when received thereby from the source of the return data.