Patent ID: 7966453

Claim:
A method for operating a computer system having a storage controller and a processing unit have a cache memory involving various ownership states as to a cache line, which states include a read-only or shared state and an exclusive state for holding the line exclusively, for software-initiated modification by hardware while the line is in said exclusive state, comprising the steps of: activating interface controls for allowing software running on said computer system to indicate to the processing unit that its storage modification of a particular cache line in the exclusive state is done, and will not be doing any modification for the time being, for an active software indication to disown a cache line's exclusive rights, and communicating with said storage controller said software indication that its storage modification of said particular cache line is done and that any modification will not be done for the time being, executing a demote request with regard to said particular cache line indicated by said software indication in said processing unit to cause the processing unit to actively relinquish control of its exclusive ownership of said particular cache line, and preemptively updating the ownership status in the storage controller of said particular cache line to a read-only or shared state and with said preemptive updating removing delays due to cross interrogates (XIs) that would have otherwise been encountered by another processor should that another processor request an exclusive ownership to the actively relinquished particular cache line.