操作系统可以提高计算机硬件的使用效率，什么时候操作系统可以违反这条原则，并浪费资源但却是合适的

当你在计算机里运行大型程序时对资源会有很大的开销，这是正常现象，并不是浪费资源。

vista

We have stressed the need for an operating system to make efficient use of the computing hardware. When is it appropriate for the operating system to forsake this principle and to “waste” resources? Why is such a system not really wasteful?
Answer:
Single-user systems should maximize use of the system for the user. A GUI might “waste” CPU cycles, but it optimizes the user’s interaction with the system.
这是书上的原话