Processing unit with an improved ability to coordinate the execution of multiple tasks with varying priorities

摘要

The present invention provides a processing unit with an improved ability to coordinate the execution of multiple tasks with varying priorities. Tasks to be executed are assigned both a request condition and a terminating condition, with the processing unit initiating execution of the task with the highest priority whose request condition is satisfied. In general, the processing unit terminates an executing task once the terminating condition of that task is satisfied, and then initiates execution of the next highest-priority task with a satisfied request condition. However, the processing unit may abort execution of a task (other than the highest-priority task) if the request condition of a higher-priority task becomes satisfied. Moreover, the processing unit ensures the highest-priority task does not monopolize system resources by tracking the elapsed execution time and terminating the highest-priority task if this elapsed time exceeds a predetermined maximum, in which case the processing unit initiates execution of the next highest priority task with a satisfied request condition.