Methods and apparatus for speculative probing of a remote cluster

A computer system, comprising:

• a first cluster including a first plurality of processors and a first cache coherence controller, the first plurality of processors and the first cache coherence controller interconnected in a point-to-point architecture;
• a second cluster including a second plurality of processors and a second cache coherence controller, the second plurality of processors and the second cache coherence controller interconnected in a point-to-point architecture, the first cache coherence controller coupled to the second cache coherence controller;
• wherein the second cache coherence controller is configured to receive a cache access request originating from the first plurality of processors and send a first probe to a third cluster including a third plurality of processors before the cache access request is received by a serialization point in the second cluster.

A computer system, comprising:

• a first cluster including a first plurality of processors and a first cache coherence controller, the first plurality of processors and the first cache coherence controller interconnected in a point-to-point architecture;
• a second cluster including a second plurality of processors and a second cache coherence controller, the second plurality of processors and the second cache coherence controller interconnected in a point-to-point architecture, the first cache coherence controller coupled to the second cache coherence controller and constructed to receive a cache access request originating from the first plurality of processors and send a probe to a third cluster including a third plurality of processors before a memory line associated with the cache access request is locked.

A cache coherence controller, the cache coherence controller comprising:

• interface circuitry coupled to a home cluster processor in a home cluster and a remote cluster cache coherence controller in a remote cluster;
• a protocol engine coupled to the interface circuitry, the protocol engine configured to receive a cache access request from a request cluster and speculatively probe a remote node in the remote cluster.