Methods and apparatus for speculative probing of a remote cluster
DCFirst Claim
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1. A computer system, comprising:
- a request cluster including a plurality of interconnected request cluster processors and a request cluster cache coherence controller;
a home cluster including a plurality of interconnected home processors, a serialization point, and a home cache coherence controller; and
a remote cluster including a plurality of interconnected remote processors and a remote cache coherence controller, wherein the remote cluster is configured to receive a first probe corresponding to a cache access request from a request cluster processor in the request cluster and a second probe corresponding to the cache access request from the home cluster.
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Abstract
According to the present invention, methods and apparatus are provided for increasing the efficiency of data access in a multiple processor, multiple cluster system. Techniques are provided for speculatively probing a remote cluster from either a request cluster or a home cluster. A speculative probe associated with a particular memory line is transmitted to the remote cluster before the cache access request associated with the memory line is serialized at a home cluster. When a non-speculative probe is received at a remote cluster, the information associated with the response to the speculative probe is used to provide a response to the non-speculative probe.
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Citations
36 Claims
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1. A computer system, comprising:
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a request cluster including a plurality of interconnected request cluster processors and a request cluster cache coherence controller;
a home cluster including a plurality of interconnected home processors, a serialization point, and a home cache coherence controller; and
a remote cluster including a plurality of interconnected remote processors and a remote cache coherence controller, wherein the remote cluster is configured to receive a first probe corresponding to a cache access request from a request cluster processor in the request cluster and a second probe corresponding to the cache access request from the home cluster. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for a cache coherence controller to manage data access in a multiprocessor system, the method comprising:
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receiving a cache access request from a request cluster processor associated with a request cluster;
forwarding the cache access request to a home cluster, the home cluster including a home cluster cache coherence controller and a serialization point; and
sending a probe associated with the cache request to a remote cluster. - View Dependent Claims (12, 13, 14)
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15. A computer system, comprising:
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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 first cache coherence controller is configured 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 the cache access request is received by a serialization point in the second cluster. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A computer system, comprising:
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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.
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22. A cache coherence controller, the cache coherence controller comprising:
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interface circuitry coupled to a request cluster processor in a request 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 the request cluster processor and speculatively probe a remote node in the remote cluster. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A cache coherence controller, comprising:
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means for receiving a cache access request from a request cluster processor associated with a request cluster;
means for forwarding the cache access request to a home cluster, the home cluster including a home cluster cache coherence controller and a serialization point; and
means for sending a probe associated with the cache request to a remote cluster.
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Specification