Organizing tasks by a hierarchical task scheduler for execution in a multi-threaded processing system
A method for scheduling tasks from a program executed by a multi-processor core system is disclosed. The method includes a scheduler that groups a plurality of tasks, each having an assigned priority, by priority in a task group. The task group is assembled with other task groups having identical priorities in a task group queue. A hierarchy of task group queues is established based on priority levels of the assigned tasks. Task groups are assigned to one of a plurality of worker threads based on the hierarchy of task group queues. Each of the worker threads is associated with a processor in the multi-processor system. The tasks of the task groups are executed via the worker threads according to the order in the hierarchy.
1. A multi-thread system, comprising:
a first processor core configured to schedule, at a first time, a first plurality of tasks of a first task group to be concurrently executed on a first plurality of worker threads; and
a second processor core configured to acquire a next task of the first plurality of tasks via an atomic exchange function performed on a pointer to a position in the first plurality of tasks, wherein:
the second processor, in response to the completion of a first task by a first worker thread of the first plurality of worker threads, acquires the next task for the first plurality of worker threads;
the first processor core is further configured to schedule, at a second time after the first time, a second plurality of tasks to be concurrently executed on the first plurality of worker threads;
the second processor core is configured to determine, via a result of the atomic exchange function, that the first plurality of tasks is completed;
the second processor core is configured to determine, via a result of the atomic exchange function, that the first task group is completed; and
the second processor core is configured to trigger a synchronized exit from the first task group by the first plurality of worker threads.
2. The multi-thread system of claim 1 , wherein the atomic exchange function is an atomic increment function.
3. The multi-thread system of claim 1 , wherein the atomic exchange function is an atomic add function.
4. The multi-thread system of claim 1 , wherein second processor core is configured to, based at least upon the determination that the first task group is completed, send a task group status signal to the first processor core, the task group status indicating that the first task group is completed.
5. The multi-thread system of claim 4 , wherein the first processor core is configured, based at least upon the task group status signal, to schedule a second plurality of tasks of a second task group to be concurrently executed on a second plurality of worker threads, the second plurality of worker threads comprising one or more worker threads of the first plurality of worker threads.