Methods and apparatus for speculative probing of a remote cluster

US 7,103,636 B2
Filed: 05/28/2002
Issued: 09/05/2006
Est. Priority Date: 05/28/2002
Status: Expired due to Fees

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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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36 Claims

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.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- - 2. The computer system of claim 1, wherein the first probe is a speculative probe.
  - 3. The computer system of claim 2, wherein the second probe is a non-speculative probe.
  - 4. The computer system of claim 2, wherein the results of the first probe are used in a probe response corresponding to the second probe.
  - 5. The computer system of claim 4, wherein the first probe is dropped if the second probe is received before the first probe.
  - 6. The computer system of claim 4, wherein the first probe is dropped if a third probe corresponding to a memory line associated with the cache access request is received before the first probe.
  - 7. The cache coherence controller of claim 6, wherein the request cluster cache coherence controller is constructed to act as an aggregate remote cache.
  - 8. The cache coherence controller of claim 6, wherein the request cluster cache coherence controller is constructed to act as a probing agent pair.
  - 9. The cache coherence controller of claim 6, wherein the request cluster cache coherence controller is constructed to act as a remote memory.
  - 10. The cache coherence controller of claim 6, wherein the request cluster cache coherence controller is constructed to act as a remote processor.

11. A method for a cache coherence controller to manage data access in a multiprocessor system, the method comprising:
- 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)
- - 12. The method of claim 11, wherein sending the probe associated with the cache request comprises sending a probe to a remote cluster cache coherence controller before a memory line associated the probe is locked.
  - 13. The method of claim 11, wherein a plurality of request cluster processors in the request cluster share a memory address space with a plurality of home processors in the home cluster.
  - 14. The method of claim 11, wherein sending the probe to the remote cluster comprises sending a probe to the remote node before a request associated with the probe is received at a memory access serialization point.

15. 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 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)
- - 16. The computer system of claim 15, wherein the memory access serialization point is a memory controller in the second cluster.
  - 17. The computer system of claim 16, wherein the probe is associated with the memory line corresponding to the cache access request.
  - 18. The computer system of claim 15, wherein the third cluster includes a third cache coherence controller.
  - 19. The computer system of claim 17, wherein the third cache coherence controller is further configured to receive a probe originating from the second cluster and respond to the probe originating from the second cluster using information obtained from the probe of the first plurality of processors.
  - 20. The computer system of claim 19, further comprising a pending buffer associated with the first cache coherence controller.

21. 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.

22. A cache coherence controller, the cache coherence controller comprising:
- 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)
- - 23. The cache coherence controller of claim 22, wherein the protocol engine is further configured to speculatively probe the remote node by sending a probe to the remote node before a memory line associated the probe is locked.
  - 24. The cache coherence controller of claim 22, wherein the request cluster processor shares a memory address space with a remote cluster processor.
  - 25. The cache coherence controller of claim 24, wherein the request cluster includes a plurality of processors interconnected in a point-to-point architecture.
  - 26. The cache coherence controller of claim 24, wherein the remote cluster includes a plurality of processors interconnected in a point-to-point architecture.
  - 27. The cache coherence controller of claim 22, wherein the protocol engine is further configured to speculatively probing a remote node by sending a probe to the remote cache coherence controller associated with the remote node before a request associated with the probe is received at a memory access serialization point.
  - 28. The cache coherence controller of claim 27, wherein the memory access serialization point is a memory controller in a home cluster.
  - 29. The cache coherence controller of claim 22, wherein the cache coherence controller is constructed to act as an aggregate remote cache.
  - 30. The cache coherence controller of claim 22, wherein the cache coherence controller is constructed to act as a probing agent pair.
  - 31. The cache coherence controller of claim 22, wherein the cache coherence controller is constructed to act as a remote memory.
  - 32. The cache coherence controller of claim 22, wherein the cache coherence controller is constructed to act as a remote processor.
  - 33. The cache coherence controller of claim 22, wherein the protocol engine, the request cluster processor, and the remote cluster processor support a coherence protocol.
  - 34. The cache coherence controller of claim 33, wherein the request cluster cache coherence controller is coupled to the remote cluster cache coherence controller through a point-to-point architecture.
  - 35. The cache coherence controller of claim 33, wherein the request cluster cache coherence controller is coupled to the remote cluster cache coherence controller through a switch architecture.

36. A cache coherence controller, comprising:
- 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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Current Assignee
Sanmina-SCI Corporation
Original Assignee
Newisys, Inc. (Sanmina-SCI Corporation)
Inventors
Glasco, David B.
Primary Examiner(s)
Verbrugge, Kevin

Application Number

US10/157,388
Publication Number

US 20030225979A1
Time in Patent Office

1,561 Days
Field of Search

709206-213, 709216-218, 709/219, 711141-146
US Class Current

709/206
CPC Class Codes

G06F 12/0815   Cache consistency protocols

G06F 2212/2542   Non-uniform memory access [...

G06F 2212/507   using speculative control

Methods and apparatus for speculative probing of a remote cluster

First Claim

11 Assignments

Litigations

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Abstract

102 Citations

36 Claims

Specification

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Methods and apparatus for speculative probing of a remote cluster

First Claim

11 Assignments

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Litigations

0 Petitions

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Accused Products

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Abstract

102 Citations

36 Claims

Specification

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Use Cases

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Others