摘要： 针对手持终端高实时性和多任务的特点,在内核中增加编译实时互斥锁、线程化中断、高精度定时器和动态时钟等实时机制。基于RM算法和SCHED_FIFO算法相结合的思想,提出任务集分类调度策略,根据截止期调度算法硬实时性高的特点,分别使用截止期调度算法与实时组调度算法调度硬实时任务与软实时任务。理论推导和实验结果表明,改进后Linux内核的实时性能指标符合硬实时任务的微秒级要求,并且当系统过载时能有效降低任务的截止期错失率,在1.2~2.8的CPU负载区间内平均降幅达到18%。

关键词: 手持终端, 内核实时机制, 动态时钟, 实时组调度, 截止期调度, 分类调度

Abstract: According to the high real-time performance and multitasking features of the handheld terminal,some real-time mechanisms are added to the kernel,such as real-time mutual exclusion lock,threaded interruption,high precision timer and dynamic clock.Based on the idea of the RM algorithm combined with SCHED_FIFO algorithm,a taskset classified scheduling strategy is proposed.Considering the deadline scheduling algorithm has the feature of high hard real-time performance,deadline scheduling algorithm is used to schedule hard real-time task and real-time group scheduling algorithm is used to schedule soft real-time task.Theoretical derivation and experimental results show that the real-time performance of the improved Linux kernel meets the microsecond requirements of hard real-time tasks,and it also can reduce the tasks’ deadline missing rate effectively when the system is overloaded.The average deadline missing rate is dropped by 18% when CPU load range is between 1.2 and 2.8.

Key words: handheld terminal, kernel real-time mechanism, dynamic clock, real-time group scheduling, deadline scheduling, classified scheduling

中图分类号: 

• TP399