Binary chop type task dispatching method for embedding real-time operating system

Abstract

State mask is adopted in the method to indicate ready state of user's task in a task table arranged in sequence according to priority high and low. Then, dichotomy search is realized by using shift comparison to locate task with highest priority rapidly, based on which, despatcher carries out task scheduling and switching. The method uses first level mask to indicate priority distribution of tasks in ready state. Dichotomy search is utilized to raise efficiency for locating task with highest priority, and to reduce number of time for accessing memory. The invention possesses advantages of stable dispatching time delay, high efficiency and less memory space used. The method implemented in MPC555 hardware platform is as a part of Tsinghua open system of electrical car (Tsinghua OSEK).

Description

technical field [0001] The binary search type task scheduling method of an embedded real-time operating system belongs to the technical field of embedded real-time operating systems, and in particular relates to an embedded real-time operating system based on a PowerPC processor structure. technical background [0002] Task scheduling is one of the cores of a multitasking operating system. The main function of task scheduling is to select a ready user task from user tasks according to certain rules, and jump to the user task for execution. Most embedded real-time operating system kernels are based on priority scheduling, that is, each task is given a priority value according to its importance, and the scheduler always chooses the ready task with the highest priority to run. Common priority-based scheduling methods include time slice round-robin and first-in-first-out. [0003] Task scheduling is mainly implemented by the scheduler. In order to implement the above scheduli...

AI Technical Summary

Problems solved by technology

In the existing public technology, there is a sequential traversal ready task queuing method or an improved traversal queuing method. The structure variables used in this method are simple and flexible, but the time consumption is unstable. In the worst case, the entire task queue must be traversed. Therefore, when there are many priorities, the longest traversal delay is unacceptable for real-time systems

Some real-time operating systems such as μC / OS-II use the grouping mapping table method, which is time-consuming, stable and highly efficient, but the structure variables of this method are complex, the storage space used is large, and it is not conducive to dynamically changing the priority

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