发明授权
US06785774B2 High performance symmetric multiprocessing systems via super-coherent data mechanisms 失效
通过超相干数据机制的高性能对称多处理系统

High performance symmetric multiprocessing systems via super-coherent data mechanisms
摘要:
A multiprocessor data processing system comprising a plurality of processing units, a plurality of caches, that is each affiliated with one of the processing units, and processing logic that, responsive to a receipt of a first system bus response to a coherency operation, causes the requesting processor to execute operations utilizing super-coherent data. The data processing system further includes logic eventually returning to coherent operations with other processing units responsive to an occurrence of a pre-determined condition. The coherency protocol of the data processing system includes a first coherency state that indicates that modification of data within a shared cache line of a second cache of a second processor has been snooped on a system bus of the data processing system. When the cache line is in the first coherency state, subsequent requests for the cache line is issued as a Z1 read on a system bus and one of two responses are received. If the response to the Z1 read indicates that the first processor should utilize local data currently available within the cache line, the first coherency state is changed to a second coherency state that indicates to the first processor that subsequent request for the cache line should utilize the data within the local cache and not be issued to the system interconnect. Coherency state transitions to the second coherency state is completed via the coherency protocol of the data processing system. Super-coherent data is provided to the processor from the cache line of the local cache whenever the second coherency state is set for the cache line and a request is received.
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