to Directory Protocol Messages Message Type Source Destination Message Function Read miss Home Processor p has a read miss at address a Cache Directory Request data and make p a read sharer Local Home Write miss Processor p has a write miss at address a Cache Directory Request data and make p the exclusive owner Invalidate Local Home Processor P wants to invalidate all copies of the same Cache Directory block at address a in all remote caches Invalidate ome Remote Directory sends invalidate message to all remote caches to Directory Caches invalidate shared block at address a Acknowledge Remote Home Remote cache sends an acknowledgement message back Cache Directory to home directory after invalidating last shared block a Acknowledge Home oca Directory sends acknowledgment message back to local Directory Cache cache of p after invalidating all shared copies of block a Home Remote Directory sends a fetch message to a remote cache to fetch Directory Cache block a and to change its state to shared Fetch Home Remote Directory sends message to a remote cache to fetch block Invalidate Directory Cache A and to change its state to invalid Data block Director Local Directory or remote cache sends data block reply message Reply or Cache Cache to local cache of processor P that requested data block A Data block Remote Home Remote Cache sends a write-back message to home Write Back Cache Director directory containing data block A 2021/22 计算机体系结构Directory Protocol Messages 2021/2/2 计算机体系结构 17