Question: Assume a directory-based cache coherence protocol. The directory currently has information that indicates that processor P1 has the data in exclusive mode. If the directory

Assume a directory-based cache coherence protocol. The directory currently has information that indicates that processor P1 has the data in “exclusive” mode. If the directory now gets a request for the same cache block from processor P1, what could this mean? What should the directory controller do? (Such cases are called race conditions and are the reason why coherence protocols are so difficult to design and verify.)

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