l*****n
发帖数: 3 | 1 We are working on a new processor, techium 5, which is going to replace the
old Techium 4. Techium 5 has new ISA with more registers, which
1. Reduces the number of memory instructions by 50 %
2. While increasing the number of simple ALU instructions by 10%
Additionally, Techium 4 has a clock frequency of 2GHzm while Techium 5 uses
3GHz.
The two processors have the same average CPI for each type of instruction—
1 CPI for simple ALU, 3 CPI for memory
2 CPI for all other instructions
A professor mostly runs a project grading script grading script on this
laptop. A run of this script, with the Techium 4 processor, resulting in
executing 50 billion simple ALU instructions, 10 billion memory instructions
, and 40 billion other instructions.
How long does this script run on Techium 4?
How long does this script run on Techium 5 |
a*o
发帖数: 19981 | 2 尼玛隔行如隔山，哥题目都只看了个囫囵个儿，好几个缩写只能猜。。。
the
uses
【在 l*****n 的大作中提到】
: We are working on a new processor, techium 5, which is going to replace the
: old Techium 4. Techium 5 has new ISA with more registers, which
: 1. Reduces the number of memory instructions by 50 %
: 2. While increasing the number of simple ALU instructions by 10%
: Additionally, Techium 4 has a clock frequency of 2GHzm while Techium 5 uses
: 3GHz.
: The two processors have the same average CPI for each type of instruction—
: 1 CPI for simple ALU, 3 CPI for memory
: 2 CPI for all other instructions
: A professor mostly runs a project grading script grading script on this
|
z*********e
发帖数: 10149 | 3 CPU time = Sigma(# of instructions * CPI * Clock)
想不出来跟
1. Reduces the number of memory instructions by 50 %
2. While increasing the number of simple ALU instructions by 10%
有什么关系呢？ |
l*****n
发帖数: 3 | 4
我不知道他是不是用不同的处理器所以处理script的方式也不一样，instruction的数
量可能变化了，如果没有变化的话，那不是只有cycle time会影响吗
【在 z*********e 的大作中提到】
: CPU time = Sigma(# of instructions * CPI * Clock)
: 想不出来跟
: 1. Reduces the number of memory instructions by 50 %
: 2. While increasing the number of simple ALU instructions by 10%
: 有什么关系呢？
|
d***a
发帖数: 13752 | 5 难道不先说清楚是single issue，in-order pipeline。:)
实际的处理器中，没有哪个2-3 GHz的处理器是single issue, in-order的了。
要解也很简单，CPU time = # instructions * CPI * clock cycle time，分别对ALU
，memory和others做计算，再求和。
Reduces the number of memory instructions by 50%的意思是，在Techium 4上执行
程序运行时有10 billion memory instructions。在Techium 5上，因为指令集变了（
编译器也变了），源程序相同，执行程序变得不同，执行程序运行时memory
instructions的数目减少到了5 billion了。
the
uses
【在 l*****n 的大作中提到】
: We are working on a new processor, techium 5, which is going to replace the
: old Techium 4. Techium 5 has new ISA with more registers, which
: 1. Reduces the number of memory instructions by 50 %
: 2. While increasing the number of simple ALU instructions by 10%
: Additionally, Techium 4 has a clock frequency of 2GHzm while Techium 5 uses
: 3GHz.
: The two processors have the same average CPI for each type of instruction—
: 1 CPI for simple ALU, 3 CPI for memory
: 2 CPI for all other instructions
: A professor mostly runs a project grading script grading script on this
|
l*****n
发帖数: 3 | 6
ALU
我最开始也是这么理解的，如果说是这样的话，那4的运算时间应该是0.08秒，5应该是
0.05秒，这样的话5的alu变成了55million了也就。可是我把答案放上去了还是不对，
是我算错了吗？还是有别的可能性？
【在 d***a 的大作中提到】
: 难道不先说清楚是single issue，in-order pipeline。:)
: 实际的处理器中，没有哪个2-3 GHz的处理器是single issue, in-order的了。
: 要解也很简单，CPU time = # instructions * CPI * clock cycle time，分别对ALU
: ，memory和others做计算，再求和。
: Reduces the number of memory instructions by 50%的意思是，在Techium 4上执行
: 程序运行时有10 billion memory instructions。在Techium 5上，因为指令集变了（
: 编译器也变了），源程序相同，执行程序变得不同，执行程序运行时memory
: instructions的数目减少到了5 billion了。
:
: the
|
d***a
发帖数: 13752 | 7 啊，你把小数点算错了三位。第一个时间应该是80秒。
【在 l*****n 的大作中提到】
:
: ALU
: 我最开始也是这么理解的，如果说是这样的话，那4的运算时间应该是0.08秒，5应该是
: 0.05秒，这样的话5的alu变成了55million了也就。可是我把答案放上去了还是不对，
: 是我算错了吗？还是有别的可能性？
|
m********n
发帖数: 3812 | 8 pretend there is a job offer opening, and set this as the interview question
.
then tell all the applications that so sorry, maybe next time. |
