基于μC/OS-Ⅱ实时系统分层混合调度算法的研究

On μC/OS-Ⅱ Real-time Mixed Type Duty Dispatch

对于实时混合型任务调度,基于NP问题的分析研究,在分层中采用基于阈值的双优先级调度算法,该算法结合了抢占式与非抢占式调度算法的优点,可以提高任务集的调度成功率,并减少由于任务切换引起的系统开销。对阈值的分配是调度算法的核心。在基本优先级已知的条件下,基于回溯技术的阈值分配算法利用低端任务阈值单向影响高端任务最大响应时间的特性,可以在有限的时间内为任务集找出一组具有极大值特征的阈值。该组阈值可以将任务切换次数降至最低,使各队列能够将任务的分配达到一个利用率很好的程度。

Regarding real -time mixed type duty dispatch, based on NP question analysis research, The threshold based dual- level priority algorithm integrates preemptive scheduling and non - preemptive scheduling in the layer - model. The schedule ability of jobs can be improved by the algorithm, and the system overhead introduced by preemption can be reduced, too. Assigning thresholds is in the core of the algorithm. The response time of lower priority job can not be affected by thresholds of higher priority jobs while inverse is not. Assuming that job priorities are already known, the job can be assigned a set of maximum thresholds which can improve the performance of the scheduling algorithm. Enables various queue to achieve the duty assignment a use factor very good degree.