Input/Output,modern operating system, 3rd edition

memory-mapped I/O will have trouble on caching.
关于中断：因为现代处理器都是流水线或者超标量，所以中断已经不是precise,而是mprecise.
硬件的中断控制和OS的中断处理会非常复杂。

principles of I/O software:device independence and error handling

I/O software layers

我们用中断处理I/O，但是却需要在驱动层尽量屏蔽中断而选择阻塞。the driver can block itself by doing a down on a semaphore,a wait on a condition variable,a receive on a message,or something similar.

power issue:the top three energy sinks in computer are display,disk,and CPU,in that order.