Method for constructing Share-F state in local domain of multi-level cache consistency domain system

Abstract

The invention discloses a method for constructing a Share-F (Forwarding) state in a local domain of a multi-level cache consistency domain system. The method comprises the following steps of: 1), when requesting to visit remote data of an S (Shared) state with the same address, determining a visiting data copy by enquiring a remote agent directory RDIR, and judging whether the data copy is in an internodal S state and an intranodal F state; 2), directly forwarding the data copy to a requester, and setting a data copy record of the current requester as an internodal Cache consistency domain S state and an intranodal Cache consistency domain F state, and 3), after forwarding the data, setting an intranodal processor record losing an F right state as an internodal Cache consistency domain S state and an intranodal Cache consistency domain F state in the remote data directory RDIR. The method can reduce the frequency and overhead of trans-node visiting, and therefore, greatly improves the performances of the two-level or multilevel Cache consistency domain CC-NUMA system.

Description

technical field [0001] The invention relates to the field of computer architecture, in particular to a method for constructing a Share-F state in a multi-level cache coherence domain system local domain. Background technique [0002] The MESIF protocol is widely used in distributed shared memory computer systems to maintain the global Cache coherence of multiple Cache replica systems. Among them: 1) The M (Modified) state is a modified state, indicating that the cached data is in a modified state in a certain CPU, and the data is inconsistent with the corresponding data in the root memory, which is the only latest copy of the entire system; when the CPU When the data is replaced or other CPUs apply to access the data, a global consistency operation will inevitably be triggered to write the data back to the root memory and update the corresponding data in the root memory. 2) The E (Exclusive) state is an exclusive state, indicating that the cache data is exclusive in a certa...

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Problems solved by technology

[0008] However, it must be noted that the MESIF protocol cannot solve the problem of mutual forwarding of S-state data between processors in a node (assuming that a cached data of the node is in S-state), that is, other processors in the node cannot directly obtain from the processor in the S-state of the node. The S-state cache data copy must send a request to the root node of the data across nodes and obtain the data from other nodes with F-state data, thus increasing the frequency and processing overhead of processor cross-node access

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