chapter5-m3-ziavras

Identity of requesting processor is added to set

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Unformatted text preview: requesting processor. The state of the block is made Exclusive. 31 Example Directory Protocol • Block is Exclusive: current value of the block is held in the cache of the processor identified by the set Sharers (the owner) => three possible directory requests: – Read miss: owner processor is sent data fetch message, causing state of block in owner’s cache to transition to Shared and causes owner to send data to directory, where it is written to memory & sent back to di requesting processor. Identity of requesting processor is added to set Sharers, which still contains the identity of the processor that was the owner (since it still has a readable copy). State is shared. – Data write-back: owner processor is replacing the block and hence must write it back, making memory copy up-to-date (the home directory essentially becomes the owner), the block is now (the home directory essentially becomes the owner), the block is now Uncached, and the Sharer set is empty. – Write mi...
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This document was uploaded on 02/09/2014.

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