问题 单项选择题

设指令由取指、分析和执行3个子部件完成;并且每个子部件的时间均为Δt。若采用度为4的超标量流水线处理机,连续执行12条指令,共需花费()Δt。

A.3 

B.5 

C.9 

D.14

答案

参考答案:B

解析:

指令由取指、分析和执行3个子部件完成,n=3,且每个子部件的时间均为止Δt。若采用常规标量单流水线处理机(即该处理机的度m=1),连续执行12条(k=-12)指令的时空图如图2-12所示。执行这12条指令所需的总时间为:Tk=(k+3-1)Δt=(12+3)Δt=14Δt。 

若采用度为4(m=4)的超标量流水线处理机,连续执行上述12条(k=12)指令的时空图如图2-13所示。 

由图2-`13可知,执行这12条指令所需的总时间只需要5Δt。

多项选择题
阅读理解

Winter-swimming has become popular in Beijing. Three years ago, few people would go swimming in the icy waters. But now there is a Winter-swimming Enthusiasts’ Club(冬泳爱好者协会)and it has more than 2,000 members. The oldest is 84 years old and the youngest is only 7. The members are from all walks of life. They may be workers, peasants, soldiers, teachers, students…

Though it is now the coldest part of the season and the water temperature in the city’s lakes is around 0℃, many winter-swimmers still swim in the icy waters, even when it is snowing. They enjoy themselves in the lake, while the people by the side of the lake are wearing heavy clothes.

Why are so many people interested in winter-swimming? Because winter-swimming can be good for one’s health.

Bei Sha is a good example. He is 69, and he once suffered from(患……病)heart trouble for 26 years. After ten years of winter-swimming he is now in good health. Scientists are now studying the effects of winter-swimming on health.

小题1: Among the winter-swimmers the oldest man is_______ years older than the youngest one.

A.91

B.84

C.77

D.7小题2: Guess what “The members are from all walks of life” means?

A.The members do different jobs at different places.

B.They come from all parts of Beijing.

C.They are persons of different ages.

D.They are men and women, old and young.小题3: The winter-swimmers are able to swim in the icy waters, even on snowy days because       .

A.they are not afraid of coldness

B.they often swim in the icy waters

C.they know that they can benefit(得益)from it

D.winter-swimming can make people healthy小题4: Winter-swimming has become popular in Beijing because       .

A.more and more people like to swim in Beijing

B.it is more interesting than swimming in summer

C.winter-swimmers are brave men

D.winter-swimming does a lot of good to one’s health小题5: What’s the best title for this passage?

A.People in Beijing Like Swimming in Winter

B.Winter-swimming—A Craze(狂热)in Beijing

C.People Benefit from Winter-swimming

D.Winter-swimmers Are Brave Men