Complete the following questions on CPU performance and show all of your work. F
ID: 3816592 • Letter: C
Question
Complete the following questions on CPU performance and show all of your work. For longer decimal results, round to three decimal places. 1. Suppose you wish to run a program P with 5 times 10^9 instructions on a 3 GHz machine with a CPI of 2.3. What is the expected CPU time? 2. Suppose you have the following instruction mix. What is the CPI? 3. Consider two different processors P1 and P2 executing the same instruction set with the clock rates and CPIs given in the following table. 1. If the processors each execute a program in 15 seconds, find the number of cycles and the number of instructions for each processor. 2. We are trying to reduce the program execution time by 20%, but this leads to an increase of 25% in the CPI. What clock rate should we have to get this time reduction for each processor?Explanation / Answer
1. The expected Cpu time
IC=5*10^9, CPI=2.3 and clock cycle time=3GHz=1/3*10^9
CPU time=IC*CPI*Clock cyle time
=(5*10^9) * (2.3) * (1/3*10^9) = 3.83 seconds
2) CPI will be=(0.22*2)+(0.40*1)+(0.03*2)+(0.08*1)=0.98
3)
clock_rate CPI
P1 4 2
P2 4.5 1.5
1) cycle in 15 sec
P1-> 15*4*10^9= 6*10^10 cycle.
P2-> 15*4.5*10^9 = 6.75*10^10 cycles
2) number of instructions
P1-> 6*10^10 / 2 = 3*10^10 instruictions
P2->6.75*10^10 /1.5 = 4.5*10^10 instructions.
CPI new=CPIold*1.25
then CPI(P1)=2*1.25=2.5
CPI(P2)=1.25*1.5=1.875
f= no of instructions*CPI/time
f(P1)=30*10^9 * 2.5/8= 9.375GHz
f(p2)=45*10^9 * 1.875/8= 10.55 GHz
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.