Multiple GPU graphics processing system

A graphics processing unit comprising:

• a plurality of functional units, including a management unit that provides an interface with a host processor for the graphics processing unit and is operable to partition a graphics processing task allocated to the graphics processing unit into subtasks and to distribute the subtasks for execution to a functional unit or units of the graphics processing unit;
• at least one communications bridge for connecting the graphics processing unit to at least one other graphics processing unit that can allow communication between the graphics processing unit and a connected graphics processing unit via the communications bridge;
• and
• a communications network that provides communications between the functional units of the graphics processing unit, the communications network comprising a message-based interconnect using switches, and being configurable in use to control communications between the functional units of the graphics processing unit by configuring the switches in the communication network;
• wherein:
• the communications network is further configurable in use to either allow or prevent communication with a connected graphics processing unit or units via a communications bridge or bridge by configuring the switches in the communications network;
• and:
• the graphics processing unit is capable of operating as at least one of:
• a master graphics processing unit controlling graphics processing operations on another graphics processing unit to which it is connected via its communications bridge;
• and
• a slave graphics processing unit performing graphics processing operations under the control of another graphics processing unit to which it is connected via its communications bridge.

A method of operating a graphics processing system comprising a plurality of graphics processing units, in which:

• each graphics processing unit of the plurality of graphics processing units is connected to at least one other graphics processing unit of the plurality of graphics processing units via a communications bridge or bridges that can allow communication between the connected graphics processing units, and in which:
• each graphics processing unit of the plurality of graphics processing units comprises:
• one or more execution units;
• a management unit that provides an interface with a host processor for the graphics processing unit and is operable to partition a graphics processing task allocated to the graphics processing unit into subtasks and to distribute the subtasks for execution to an execution unit or units of the graphics processing unit;
• and a communications network for providing communications between the units of the graphics processing unit, the communications network comprising a message-based interconnect using switches, and being configurable in use to control communications between the units of the graphics processing unit by configuring the switches in the communication network;
• and wherein:
• the communications network is further configurable in use to either allow or prevent communication with the at least one other graphics processing units via the communications bridge or bridges by configuring the switches in the communications network;
• the method comprising:
• enabling communication between at least two of the graphics processing units of the plurality of graphics processing units by configuring the communications networks of the at least two graphics processing units to allow communication between the at least two graphics processing units via a communications bridge or bridges of the graphics processing units;
• and
• one of the graphics processing units of the at least two graphics processing units acting as a master graphics processing unit controlling graphics processing operations on the other one or ones of the at least two graphics processing units of the plurality of graphics processing units with which it can communicate;
• and
• the other one or ones of the at least two graphics processing units acting as a slave graphics processing unit or units to perform graphics processing operations under the control of the graphics processing unit that is acting as a master graphics processing unit.

A method of operating a graphics processing system comprising a plurality of graphics processing units, in which:

• each graphics processing unit of the plurality of graphics processing units is connected to at least one other graphics processing unit of the plurality of graphics processing units via a communications bridge or bridges that can allow communication between the connected graphics processing units:
• each graphics processing unit of the plurality of graphics processing units comprises:
• one or more execution units;
• a management unit that provides an interface with a host processor for the graphics processing unit and is operable to partition a graphics processing task allocated to the graphics processing unit into subtasks and to distribute the subtasks for execution to an execution unit or units of the graphics processing unit;
• and a communications network for providing communications between the units of the graphics processing unit, the communications network comprising a message-based interconnect using switches, and being configurable in use to control communications between the units of the graphics processing unit by configuring the switches in the communication network;
• and wherein:
• the communications network is further configurable in use to either allow or prevent communication with at least one other graphics processing unit of the plurality of graphics processing units via a communications bridge or bridges by configuring the switches in the communications network;
• the method comprising:
• configuring the communications network of a graphics processing units of the plurality of graphics processing units to disable communication via a communications bridge or bridges between that graphics processing unit of the plurality of graphics processing units and the graphics processing unit or units to which it is connected via its communication bridges;
• and
• operating that graphics processing unit in a standalone mode, in which the graphics processing unit operates independently of the other graphics processing units to perform a graphics processing task.

A non-transitory computer readable storage medium storing computer software code which when executing on at least one processor performs a method of operating a graphics processing system comprising a plurality of graphics processing units, in which:

• each graphics processing unit of the plurality of graphics processing units is connected to at least one other graphics processing unit of the plurality of graphics processing units via a communications bridge that can allow communication between the connected graphics processing units, and in which:
• each graphics processing unit of the plurality of graphics processing units comprises:
• one or more execution units;
• a management unit that provides an interface with a host processor for the graphics processing unit and is operable to partition a graphics processing task allocated to the graphics processing unit into subtasks and to distribute the subtasks for execution to an execution unit or units of the graphics processing unit;
• and a communications network for providing communications between the units of the graphics processing unit, the communications network comprising a message-based interconnect using switches, and being configurable in use to control communications between the units of the graphics processing unit by configuring the switches in the communication network;
• and wherein:
• the communications network is further configurable in use to either allow or prevent communication with the at least one other graphics processing units via the communications bridge or bridges by configuring the switches in the communications network;
• the method comprising:
• enabling communication between at least two of the graphics processing units of the plurality of graphics processing units by configuring the communications networks of the at least two graphics processing units to allow communication between the at least two graphics processing units via a communications bridge or bridges of the graphics processing units;
• and
• one of the graphics processing units of the at least two graphics processing units acting as a master graphics processing unit controlling graphics processing operations on the other one or ones of the at least two graphics processing units of the plurality of graphics processing units with which it can communicate;
• and
• the other one or ones of the at least two graphics processing units acting as a slave graphics processing unit or units to perform graphics processing operations under the control of the graphics processing unit that is acting as a master graphics processing unit.