how your work in the computation for the following questions involving CPI and performance. a) Suppose you have two processors with the following...

how your work in the computation for the following questions involving CPI and performance.

a) Suppose you have two processors with the following specifications:

Processor A runs at 3.2 GHz and has a CPI of 1.8

Processor B runs at 4.4 GHz and has a CPI of 2.8

Which processor will perform better given any instruction set? How much better is the performance?

[2 marks]

b) Consider the following situation:

•

you are running a program on a 2.4 GHz processor

•

the program instructions can be divided into two categories: memory access and non-memory access

•

memory access instructions take 10 times as long as non-memory access instructions

•

20% of your instructions involve memory access

Assume you have found an optimization technique that will keep the same number of instructions, but reduce

the amount of memory access instructions to 10%. What is the improvement in the overall performance of the

optimized program compared to the original? Show your work.

[2 marks]

c) Consider the following situation:

Processor C

Base CPI, no memory stalls (including primary cache access): 2.0

Processor speed: 3.2 GHz

Main memory access time: 800 ns

Primary cache miss rate (i.e. not found in primary cache): 6%

Second-level cache direct-mapped speed: 20 cycles

Global miss rate to main memory: 2%

What is the actual CPI for this processor?

[2 marks]

d) Suppose that you have a new design for the processor described in part (c). This new design will cut the

global miss rate in half, but the tradeoff is that the access time to the second-level cache will increase. What is

the maximum number of cycles the second-level cache speed can increase to that would make this design

choice worthwhile? Justify your answer.