System controller, information processing system, and access processing method

An information processing system, comprising:

• a plurality of system controllers each coupled to at least one memory unit and an access source unit accessing the memory unit, the access source unit being configured to access any memory unit through communication between the plurality of system controllers, wherein at least any one of the plurality of system controllers comprises:
• an output unit that transfers an access request in response to the access request to the memory unit from the access source unit coupled to the system controller;
• a local snoop control unit that determines whether a destination of the access request is a local memory unit coupled to the system controller when the access source unit coupled to the system controller made an access request to the memory unit, and locks the destination when the destination is a local memory unit;
• a receiving unit that receives the access request output by the output unit of the system controller and an access request output by another system controller;
• a global snoop control unit that sends a response indicating whether the access request received by the receiving unit is executable, and controls locking of the destination when the destination of the access request received by the receiving unit is a local memory unit coupled to the system controller;
• and
• an access processing unit that performs an access to the memory unit, and unlocks the locking when the access request from the access source unit coupled to the system controller becomes executable.

An access processing method of an information processing system that includes a plurality of system controllers each coupled to at least one of a memory unit and an access source unit accessing the memory unit, the access source unit being configured to access any memory unit through communication between the plurality of system controllers, the method comprising:

• transferring an access request for accessing any of the memory units received from a local access source unit coupled to the system controller to another system controller, by the system controller;
• determining whether a destination of the received access request is a memory unit coupled to the system controller, by each of the system controllers received the transferred access request;
• locking the memory unit that is the destination of the access request, by the system controller in which the destination of the access request is a local memory unit of own system controller;
• performing the access request by the system controller received the access request from the local access source unit;
• and
• unlocking the memory unit that is a destination of the performed access request, by the system controller in which the destination of the access request is a local memory unit of own system controller.