Non-speculative distributed conflict resolution for a cache coherency protocol
First Claim
1. A method comprising:
- resolving conflicting requests from multiple peer nodes for a block of data by a peer node having a valid copy of requested data that is requested by the conflicting messages; and
resolving conflicting requests for the block of data by a home node corresponding to the requested data if no unique, cached copy is stored by one of the peer nodes.
2 Assignments
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Accused Products
Abstract
A conflict resolution technique provides consistency such that all conflicts can be detected by at least one of the conflicting requestors if each node monitors all requests after that node has made its own request. If a line is in the Exclusive, Modified or Forward state, conflicts are resolved at the node holding the unique copy. The winner of the conflict resolution, and possibly the losers, report the conflict to the home node, which pairs conflict reports and issues forwarding instructions to assure that all requesting nodes eventually receive the requested data. If a requested cache line is either uncached or present only in the Shared state, the home node provides a copy of the cache node and resolves conflicts. In one embodiment, a blackout period after all responses until an acknowledgement message has been received allows all conflicting nodes to be aware of conflicts in which they are involved.
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Citations
23 Claims
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1. A method comprising:
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resolving conflicting requests from multiple peer nodes for a block of data by a peer node having a valid copy of requested data that is requested by the conflicting messages; and
resolving conflicting requests for the block of data by a home node corresponding to the requested data if no unique, cached copy is stored by one of the peer nodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system comprising:
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a plurality of peer nodes having cache memories to generate requests for data, the peer node having a valid, cached copy of the requested data to resolve the conflicting requests and to provide a copy of the requested data to one of the multiple requesting peer nodes; and
a home node corresponding to the requested data coupled with the peer nodes, the home node to resolve the conflicting requests if no peer node stores a valid, cached copy of the requested data. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. An apparatus comprising:
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means for resolving conflicting requests from multiple peer nodes for a block of data by a peer node having a valid copy of requested data that is requested by the conflicting messages; and
means for resolving conflicting requests for the block of data by a home node corresponding to the requested data if no unique, cached copy is stored by one of the peer nodes. - View Dependent Claims (20, 21, 22)
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23-36. -36. (canceled)
Specification