摘要： 对于嵌入式系统来说，通过预测一个任务能否在绝对时限之前运行完成而决定是否调度执行是很有意义的。在ARMLinux上，为了对新任务的运行结束时间进行预测，对它的内核作了修改，按优先级排序就绪队列，每次时钟中断判断是否有优先级比当前任务更高的任务就绪，以决定是否调度，去掉了SCHED_RR调度策略，这样新任务的运行结束时间可以得到准确的计算，并根据任务的绝对时限来判断对新任务的接受和拒绝，对修改后的内核进行了试验验证。

关键词: 嵌入式操作系统, 优先级, 时限, 可调度性, 调度策略

Abstract: It is significant for an EOS to decide whether a process could be scheduled depending on whether it could be completed before absolute deadline. In order to forecast the complete time of a new process, some modifications is made in ARMLinux kernel. Run queue is ordered by real-time priority, every timer interrupt, scheduling if there is a process in run queue with higher priority than current process; deleting SCHED_RR scheduling policy. With these modifications, the complete time of a process can be forecasted in new kernel. So the decision of the acceptance or refusal for a new task can be made. The modifications for the ARMLinux kernel have been verified through test.

Key words: Embedded operating system, Priority, Deadline, Schedulability, Scheduling policy

中图分类号: 

• TP393