7.2. Waiting for I/O¶
Many types of input / output (I/O) do not occur immediately. So the process must wait in a waiting queue and the device driver needs a strategy of how to effectively wait for I/O data.
7.2.1. Polling¶
Polling is not very efficient because the system must continually check the device for data.
Note
I can not remember where I read this, but it is my understanding that only joy–sticks (game ports) use polling in modern operating systems.
7.2.2. Interrupt Driven¶
The interrupt driven approach causes drivers to consist of a top and bottom half.