We are considering making one of two adjustments to a computer. The first is to

Question

We are considering making one of two adjustments to a computer. The first is to change the CPU by applying what is called a superpipeline. In a superpipeline, the stages that access memory (instruction fetch, execution) are split into 2 or more stages. In this case, we are going to take the 6 stage pipeline from chapter 5 and make it into an 8 stage pipeline. The main advantage of doing this is that it lets us increase the clock rate. In this case, the clock rate is going from 2 GHz to 3.5 GHz. In doing so, 100% of instructions are impacted outside of stalls. The 8-stage pipeline will have 40% more stalls. The other adjustment is to increase cache memory from 16MB to 1GB which would result in less of an impact on the EAT. Specifically, this change will improve hit rate by 15%. The speedup of accessing cache over memory is 40. Which of these two enhancements should we select? Use Amdahl’s Law.

Explanation / Answer

we should use the second enhancement because this oincreases the size of the memory which allows multiple operations to take place simultaneously.This leads to an increase in the overall speedup.

speedup=1 /(s+p)/N

This means N =number of processes increases with increase in speedup.Thiis why its a better option.

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