- CPU 操作和 I/O 设备交替进行以最大化利用CPU。
- Operating systems supporting threads at the kernel level must schedule threads (NOT processes) for execution.
- 具有线程级的OS,调度的都是线程,而不是进程。
CPU调度可行:进程在CPU执行和I/O等待两个状态中切换。
CPU 调度器
- Switches from running to waiting state.
- Switches from running to ready state.
- Switches from waiting to ready.
- Terminates.
像不像一只蚂蚁在微笑🙂。
1到4的调度是无优先级的。所有其他调度都是抢占式的。
调度算法
先来先服务 First-come, first-served (FCFS)