计算机体系结构PPT教学课件-第三章流水线.ppt

Chapter 3 PIPELINING  Basic and Intermediate Concepts流水线：基本概念 Computer Architecture A Quantitative Approach A. 流水线基本定义 What is pipelining? (什么是流水线) How is the pipelining Implemented? (流水线是怎么实现的) What makes pipelining hard to implement? (流水线实现的困难是什么) Basic methods improving pipelining (提高流水线性能的一些基本方法) What is Pipelining ? Pipelining(流水线定义): “A technique designed into some computers to increase speed by starting the execution of one instruction before completing the previous one.” Modern English-Chinese Dictionary implementation technique whereby different instructions are overlapped in execution at the same time.（多条指令同时重叠执行） implementation technique to make fast CPUs Why Pipelining: Its Nature(流水线的本质) Laundry(洗衣店) Ann, Brian, Cathy, Dave each have one load of clothes to wash, dry, and fold Washer(洗衣机) takes 30 minutes Dryer(干衣机) takes 40 minutes “Folder”(叠衣人) takes 20 minutes 顺序执行的洗衣 Sequential laundry takes 6 hours for 4 loads If they learned pipelining, how long would laundry take? 流水线的洗衣 开始工作越快越好 Why pipelining : overlapped(重叠) Latches(锁存器), called pipeline registers break up computation into 5 stages Deal 5 tasks at the same time. Only deal one task each time. This task takes “ such a long time” ns: nanosecond 纳秒即十亿分之一秒 Why pipelining: more faster Can “launch(开始)” a new computation every 100ns in this structure Can finish 107 computations per second Can launch a new computation every 20ns in pipelined structure Can finish 5×107 computations per second Why pipelining : conclusion The key implementation technique used to Make fast CPU: decrease CPUtime.(减少CPU时间的关键技术) Improving of Throughput ( rather than individual execution time) (提高吞吐量，而不是单条指令的执行时间) Improving of efficiency for resources (functional unit) (提高了资源的有限利用率) What is a pipeline ? A pipeline is like an auto assemble line A pipeline has many stages(流水线有多个阶段—称流水级或流水节拍) Each stage carries out a different part of instruction or operation (每一个流水线完成指令操作的不同部分) The stage