Patent ID: 8719512
Filing Date: 2014-05-06
Classification: G06F

Abstract:
1. A system controller, comprising: an output unit that transfers an access request to a memory unit received from an access source unit coupled to the system controller to another system controller; a local snoop control unit that first determines whether data about a destination of the access request is being cached in response to the access request from the access source unit coupled to the system controller and then determines whether a destination of the received access request from the access source unit coupled to the system controller is a local memory unit coupled to the system controller when the data about the destination is not being cached, and selectively locks the destination when the data about the destination is being cached and when the destination is the local memory unit; a receiving unit that receives the access request output by the output unit and an access request output by another system controller; a global snoop control unit that sends a response indicating whether an access request received by the receiving unit is executable or not, and controls locking of the destination of the access request received by the receiving unit when the destination of the access request received by the receiving unit is the local memory unit; and an access processing unit that unlocks the locking and accesses the memory unit when the access request from the access source unit coupled to the system controller becomes executable.