Multi-socket symmetric multiprocessing (SMP) system for chip multi-threaded (CMT) processors

A system comprising:

• an interconnect;
• and
• a plurality of nodes coupled to the interconnect, wherein each of the plurality of nodes comprises:
• a plurality of processor cores, each processor core configured to have a plurality of threads active and each processor core including at least one first level cache;
• coherency control circuitry coupled to the plurality of processor cores and configured to manage intranode coherency among the plurality of processor cores;
• at least one coherence unit coupled to the coherency control circuitry and configured to couple to the interconnect, the coherence unit configured to transmit and receive coherence messages on the interconnect to maintain coherency among the plurality of nodes;
• and
• the coherency control circuitry is configured to receive a first request from the at least one coherence unit to maintain internode coherency and a second request from one of the plurality of processor cores, and the coherency control circuitry is configured to generate communications to the first level caches in the processor cores to maintain intranode coherency in response to the second request and to maintain internode coherency in response to the first request from the at least one coherence unit.

An apparatus comprising:

• a source node;
• and
• a coherence hub configured to route coherence messages between the source node and other nodes;
• wherein the source node is configured to generate a node request, which is one of the coherence messages, to initiate coherence activity for access to a given memory location, and wherein the source node is configured to assign a source identifier to the node request that identifies the source node and the node request, and wherein the coherence hub is configured to indicate that the source identifier is released for assignment to another node, and wherein the coherence hub is configured to provide the indication in another coherence message to the source node that is part of the coherence activity, if possible, and wherein the coherence hub is configured to explicitly transmit a source identifier release message to provide the indication if the indication cannot be provided in another coherence message that is part of the coherence activity.