Lightweight cooperative multi-threading

A data processing apparatus comprising:

• a scheduler;
• processing circuitry configured to perform data processing operations in response to compiled program instructions, wherein the data processing operations comprise multiple processes and wherein the data processing operations comprise operating the scheduler to support cooperative scheduling of the multiple processes,
• wherein the scheduler is configured to support the cooperative scheduling of the multiple processes with reference to a circular scheduler queue in the scheduler comprising one or more queue elements,
• wherein the multiple processes cooperate for the cooperative scheduling in that each process of the multiple processes, when active as a currently executing process, is arranged to yield execution in response to a yield instruction in the compiled program instructions of the currently executing process to allow a next process of the multiple processes to continue execution,
• wherein:
• a schedule pointer is indicative of a next queue element of the one or more queue elements,
• the scheduler is responsive to the currently executing process yielding execution to the next process:
• to initiate execution of the next process by reading context data for the next process from the next queue element and writing context data for the currently executing process to the next queue element;
• and
• to increment the schedule pointer, and
• the compiled program instructions comprise context switching instructions at a yield point in the compiled program instructions, wherein the context switching instructions are arranged to cause all live registers, other than a subset of live registers comprised by the context data for the current executing process written to the next queue element, to be saved to memory, and to cause all live registers other than the subset of live registers comprised by the context data of the next process read from the next queue element to be restored from memory.

A data processing apparatus comprising:

• means for performing data processing operations in response to compiled program instructions, wherein the data processing operations comprise multiple processes;
• scheduling means for supporting cooperative scheduling of the multiple processes, wherein the scheduler is configured to support the cooperative scheduling of the multiple processes with reference to a circular scheduler queue in the scheduler comprising one or more queue elements;
• means for executing the multiple processes cooperatively for the cooperative scheduling in that each process of the multiple processes, when active as a currently executing process, is arranged to yield execution in response to a yield instruction in the compiled program instructions of the currently executing process to allow a next process of the multiple processes to continue execution,
• wherein:
• a schedule pointer is indicative of a next queue element of the one or more queue elements,
• the scheduling means is responsive to the currently executing process yielding execution to the next process:
• to initiate execution of the next process by reading context data for the next process from the next queue element and writing context data for the currently executing process to the next queue element;
• and
• to increment the schedule pointer, and
• the compiled program instructions comprise context switching instructions at a yield point in the compiled program instructions, wherein the context switching instructions are arranged to cause all live registers, other than a subset of live registers comprised by the context data for the current executing process written to the next queue element, to be saved to memory, and to cause all live registers other than the subset of live registers comprised by the context data of the next process read from the next queue element to be restored from memory.