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发表于 2017-11-4 18:57:44
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在退出中断时，就会触发一次线程调度切换，即时切换到更高优先级的线程上。
是这么回事吗
Preemptive multitasking
Real-time operating systems like embOS operate with preemptive multitasking.
The highest-priority task in the READY state always executes as long as
the task is not suspended by a call of any operating system function.
A high-priority task waiting for an event is signaled READY as soon as the event occurs.
The event can be set by an interrupt handler, which then activates the task immediately.
Other tasks with lower priority are suspended (preempted) as long as the high-priority task is executing.
A real-time operating system, such as embOS, normally comes with a regular timer
interrupt to interrupt tasks at regular intervals and to perform task switches if timed task switches are necessary
抢先多任务
像embOS这样的实时操作系统可以抢先进行多任务操作。
该就绪状态下最高优先级的任务总是在任务不执行时执行通过任何操作系统函数调用暂停。
等待的高优先级任务一旦事件发生，一个事件就会发出READY信号。
事件可以由一个中断处理程序，然后立即激活任务。
其他任务较低只要高优先级任务正在执行，优先级就被暂停（抢占）。
一个实时操作系统，比如embOS，通常配备一个普通的定时器中断以定期中断任务，如果定时执行任务切换任务切换是必要的
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