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nba16235

Could someone help explain what this sentence mean - If action A is observed by the cache controller, action B is taken. What is action A/B and how it is related to the state?

jmackama

@nba16235: It's a legend for the diagram. For example, if the cache controller is in state S, and observes a PrWr from the local processor, it responds by sending a BusRdX. (Which will invalidate that block for any other caches)

hanzhoul

So when a processor is in M state for a cache, other processors must in I state. Is that right?

kevinle1

I believe that is true, since otherwise cache coherence wouldn't necessarily be maintained.