Patent ID: 7640315
Filing Date: 2009-12-29
Classification: G06F

Abstract:
1. In a multiprocessing computer system comprising a plurality of processing nodes interconnected through an interconnect structure, wherein the plurality of processing nodes includes a first processing node, a second processing node, and a third processing node, a method for lock request arbitration comprising: receiving a lock request at the second processing node from the first processing node; determining, at the second processing node, whether the lock request is ready for service, wherein determining whether the lock request is ready for service comprises the second processing node placing the lock request in a queue and the second processing node monitoring the queue to determine whether the lock request is ready for service; issuing a broadcast message from the second processing node to the first and the third processing nodes in response to determining that the lock request is ready for service, wherein the broadcast message informs the third processing node of servicing of the lock request, and wherein the broadcast message includes a lock bit to inform the third processing node of the servicing of the lock request; receiving a first probe response at the second processing node from the first processing node in response to sending the broadcast message; receiving a second probe response at the second processing node from the third processing node in response to sending the broadcast message, wherein the probe response is sent from the third processing node in response to the third processing node ceasing issuance of new requests; in response to receiving the first and second probe response messages, granting lock ownership to the first processing node and transmitting from the second processing node to the first processing node a lock response message to inform the first processing node of the lock ownership.