Patent ID: 6636948
Filing Date: 2003-10-21
Classification: G06F

Abstract:
A method for a processor to gain assured ownership and an up-to-date copy of data, wherein the processor is part of a multiprocessor system, the method comprising the steps of:keeping track of locations of the up-to-date data and ownership thereof, a first processor, having a copy of the data but not ownership, issuing a change-to-dirty command, CTD, that requests ownership of the data by the first processor, responding to the CTD command by, returning a success response, CTD-success, to the first processor if the first processor is unambiguously determined to have an up-to-date copy of the data, and updating only the ownership of the data while not sending data, and returning a wait for success response, CTD-check-OK, to the first processor if the first processor is not unambiguously determined to have an up-to-date copy of the data, issuing a command wherein the up-to-date copy of the data is sent to the first processor, and updating the ownership of the data.