Computer Systems A Programmer's Perspective Second Edition
In this chapter, we take a brief look at the design of processor hardware. We
study the way a hardware system can execute the instructions of a particular ISA.
This view will give you a better understanding of how computers work and the
technological challenges faced by computer manufacturers. One important con-
cept is that the actual way a modern processor operates can be quite different
from the model of computation implied by the ISA. The ISA model would seem
to imply sequential instruction execution, where each instruction is fetched and
executed to completion before the next one begins. By executing different parts
of multiple instructions simultaneously, the processor can achieve higher perfor-
mance than if it executed just one instruction at a time. Special mechanisms are
used to make sure the processor computes the same results as it would with se-
quential execution. This idea of using clever tricks to improve performance while
maintaining the functionality of a simpler and more abstract model is well known
in computer science. Examples include the use of caching in Web browsers and
information retrieval data structures such as balanced binary trees and hash tables.
在计算机科学中，用巧妙的方法在提高性能的同时，有保持一个更简单、更抽象模型的功能，
这种思想是众所周知的。在Web浏览器或平衡二叉树和哈希表这样的信息检索数据结构中使用
缓存，就是这样的例子。