Graphics processors

A data processor, the data processor comprising:

• a programmable execution unit operable to execute programs, and in which when executing a program, the programmable execution unit executes the program for respective groups of one or more execution threads, each execution thread in a group of one or more execution threads corresponding to a respective work item of an output being generated;
• and
• a plurality of registers for storing data for execution threads executing a program, each execution thread when executing a program having an associated set of registers of the plurality of registers for storing data for the execution thread,
• the data processor further comprising a processing circuit configured to, in response to a command to suspend the processing of an output being generated by the data processor:
• for a group of one or more execution threads currently executing a program for the output being generated:
• stop the issuing of program instructions for execution by the group of one or more execution threads;
• wait for any outstanding transactions that affect the content of the registers associated with the threads of the group of one or more execution threads for the group of one or more execution threads to complete;
• and
• when any outstanding transactions that affect the content of the registers associated with the threads of the group of one or more execution threads for the group of one or more execution threads have completed:
• store to memory:
• the content of the registers associated with the threads of the group of one or more execution threads;
• and
• a set of state information for the group of one or more execution threads, the set of state information including at least an indication of the last instruction in the program that was executed for the threads of the group of one or more execution threads.

A data processor, the data processor comprising:

• a programmable execution unit operable to execute programs, and in which when executing a program, the programmable execution unit executes the program for respective groups of one or more execution threads, each execution thread in a group of one or more execution threads corresponding to a respective work item of an output being generated;
• and
• a plurality of registers for storing data for execution threads executing a program, each execution thread when executing a program having an associated set of registers of the plurality of registers for storing data for the execution thread;
• the data processor further comprising a processing circuit configured to, in response to a command to resume the processing of an output being generated by the data processor whose processing was previously suspended:
• for a group of one or more execution threads whose execution of a program for the output whose processing is being resumed was stopped when the processing of the output was suspended:
• issue a corresponding group of one or more execution threads to the programmable execution unit to execute the program;
• load from memory into registers associated with threads of the issued thread group a set of register content for the threads of the thread group that was written out to memory when processing of the thread group was suspended;
• load from memory a set of thread group state information for the thread group including at least an indication of the last instruction in the program that was executed for the threads of the thread group when processing of the thread group was suspended;
• and
• after the register content and the thread group state data has been loaded:
• resume execution of the program for the issued thread group after the indicated last instruction in the program that was executed for the threads of the thread group;
• and
• use the loaded content of the registers for the threads of the issued thread group when executing the program for the issued thread group.

A non-transitory computer readable storage medium storing computer software which when executing on a processor performs a method of operating a data processor that includes a programmable execution unit operable to execute programs, and in which when executing a program, the programmable execution unit executes the program for respective groups of one or more execution threads, each execution thread in a group of execution threads corresponding to a respective work item of an output being generated, and each execution thread having an associated set of registers for storing data for the execution thread, the method comprising:

• in response to a command to suspend the processing of an output being generated by the data processor:
• for a group of one or more execution threads currently executing a program for the output being generated:
• stopping the issuing of program instructions for execution by the group of one or more execution threads;
• waiting for any outstanding transactions that affect the content of the registers associated with the threads of the group of one or more execution threads for the group of one or more execution threads to complete;
• and
• when any outstanding transactions that affect the content of the registers associated with the threads of the group of one or more execution threads for the group of one or more execution threads have completed:
• storing to memory:
• the content of the registers associated with the threads of the group of one or more execution threads;
• and
• a set of state information for the group of one or more execution threads, the set of state information including at least an indication of the last instruction in the program that was executed for the threads of the group of one or more execution threads.