CO101 Principle of Computer Organization
Assignment 1
Due: September 8, 2016
Name: Student Number:
1. Consider three different processors P1, P2, and P3 executing the same instruction set with the clock rates and CPIs given in the following table.
Processor
Clock Rate
CPI
P1
2 GHz
1.2
P2
3 GHz
0.8
P3
4 GHz
2.0
Answer the questions:
1) Which processor has the highest performance expressed in instructions per second?
The IPS for each processor: 2e9/1.2 = 1.67e9 , 3e9/0.8=3.75e9, 4e9/2.0 = 2.00e9.
2) If the processors each execute a program in 10 seconds, find the number of cycles and the number of instructions.
P1: 2.0e10 cycles, 1.67e10 ins; P2: 3.0e10 cycles, 3.75e10 ins, 4.0e10 cycles,
2.00e10 ins.
3) We are trying to reduce the time by 30% but this leads an increase of 20% in the CPI. What clock rate should we have to get this time reduction?
1/0.7 = (1+x)/1.2, x = 0.71, so clock rate need to be increased by 71%.
2. Suppose we have developed new versions of a processor with the following characteristics.
Version
Voltage
Clock Rate
Version 1
1.1 V
3 GHz
Version 2
0.8 V
4 GHz
Answer the questions:
1) How much has the capacitive load varied between versions if the dynamic power of version 2 is 24% less than version 1?
P = afv^2C, 0.76 = 4×0:8^2C2/3×1.1^2 C1 = C2/C1 = 1.0777.
2) How much has the dynamic power been reduced if the capacitive load does not change?
4×0:8^2C/3×1:1^2C = 0.70523
3) Assuming that the capacitive load of version 2 is 80% the capacitive load of version 1, find the voltage for version 2 if the dynamic power of version 2 is reduced by 20% from version 1.