chapter5-m3-ziavras

Write miss requesting processor is sent the value

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Unformatted text preview: te cache (Write back block) 30 Example Directory Protocol • Message sent to directory causes two actions: – Update the directory – More messages to satisfy request • Block is in Uncached state: the copy in memory is the current value; only possible requests for that block are: current value; only possible requests for that block are: – Read miss: requesting processor sent data from memory &requestor made only sharing node; state of block made Shared. – Write miss: requesting processor is sent the value & becomes the Sharing node. The block is made Exclusive to indicate that the only valid copy is cached. Sharers indicates the identity of the owner. • Block is Shared => the memory value is up-to-date: – Read miss: requesting processor is sent back the data from memory & requesting processor is added to the sharing set. – Write miss: requesting processor is sent the value. All processors in the set Sharers are sent invalidate messages set Sharers are sent invalidate messages, & Sharers is set to identity of Sharers is set to identity of...
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