Buffer checker for task processing fault detection

A method of processing tasks at a graphics processing system having a plurality of processing units each configured to process a task independently from any other processing unit, the method comprising, on receiving a task for processing:

• processing the task for a first time at a first processing unit so as to generate a first processed output;
• writing out the first processed output to a data store;
• reading back the first processed output from the data store and forming a first signature which is characteristic of the first processed output as read back from the data store;
• processing the task for a second time at a second processing unit so as to generate a second processed output, and forming a second signature which is characteristic of the second processed output, wherein the second signature is formed prior to the second processed output being written to the data store;
• comparing the first and second signatures;
• and
• raising a fault signal if the first and second signatures do not match.

A non-transitory computer readable storage medium having stored thereon a computer readable dataset description of an integrated circuit that, when processed in an integrated circuit manufacturing system, causes the integrated circuit manufacturing system to manufacture a graphics processing system for operation with a data store, the graphics processing system comprising:

• one or more processing units for processing tasks;
• a check unit operable to form a signature which is characteristic of an output from processing a task on a processing unit;
• and
• a fault detection unit operable to compare signatures formed at the check unit;
• wherein the graphics processing system is operable to process each task first and second times at the one or more processing units so as to, respectively, generate first and second processed outputs, the graphics processing system being configured to:
• write out the first processed output to the data store,
• read back the first processed output from the data store,
• form at the check unit a first signature which is characteristic of the first processed output as read back from the data store,
• form at the check unit a second signature which is characteristic of the second processed output, wherein the second signature is formed prior to the second processed output being written to the data store,
• compare the first and second signatures at the fault detection unit, and raise a fault signal if the first and second signatures do not match.