Life Cycle of an o Request(VO请求的周期) vO competed put data available, or output compote anster data (d appropriate)to process. satisfy request retum completion or error code send request to device driver. block process if appropriate vO subsystem process request, an command to controlle determine which IO completed configure controller to ndicate state change to vo subsystem block until interrupted receive interrupt. device contro or commands store data in devce drivor bufer d npu signal to unblock device drive monitor devoe keyboard VO completed interrupt when vO completed device generate interrupt Applied Operating System Concepts Silberschatz, Galvin, and Gagne @199912.18 Silberschatz, Galvin, and Gagne ©1999 Applied Operating System Concepts Life Cycle of an I/O Request（I/O请求的周期）