Scalable cache coherency protocol
    18.
    发明授权

    公开(公告)号:US11947457B2

    公开(公告)日:2024-04-02

    申请号:US18058105

    申请日:2022-11-22

    Applicant: Apple Inc.

    CPC classification number: G06F12/0815 G06F12/0831 G06F2212/1032

    Abstract: A scalable cache coherency protocol for system including a plurality of coherent agents coupled to one or more memory controllers is described. The memory controller may implement a precise directory for cache blocks from the memory to which the memory controller is coupled. Multiple requests to a cache block may be outstanding, and snoops and completions for requests may include an expected cache state at the receiving agent, as indicated by a directory in the memory controller when the request was processed, to allow the receiving agent to detect race conditions. In an embodiment, the cache states may include a primary shared and a secondary shared state. The primary shared state may apply to a coherent agent that bears responsibility for transmitting a copy of the cache block to a requesting agent. In an embodiment, at least two types of snoops may be supported: snoop forward and snoop back.

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