Answer:
Processor P2 has the highest performance expressed in instructions per second.
Explanation:
Given:
Processors:
P1
P2
Clock rate of P1 = 3 GHz
Clock rate of P2 = 3 GHz
Cycles per instruction = CPI of P1 = 1.5
Cycles per instruction = CPI of P2 = 1.0
To find:
which processor has the highest performance in instructions per second (IPS)
Solution:
Compute CPU time:
CPU time = (Number of instructions * cycles per instruction) / clock rate
CPU time = (I * CPI) / R
We are given the CPI and clock rate. So
CPU time = (I * CPI) / R
I / CPU time = R/CPI
Since
Instructions per second = Number of instructions (I) / execution time
IPS = I / CPU time
So
Instructions Per Second = clock rate / cycles per instruction
IPS = R/CPI
Putting the values in above formula:
Instructions Per Second for P1 = IPS (P1)
= clock rate P1 / CPI (P1)
= 3 GHz / 1.5
IPS (P1) = 2
As 1 GHz = 10⁹ Hz
IPS (P1) = 2x10⁹
Instructions Per Second for P2 = IPS (P2)
= clock rate P2 / CPI (P2)
= 3 / 1.0
IPS (P2) = 3
As 1 GHz = 10⁹ Hz
IPS (P2) = 3x10⁹
Hence processor P2 has the highest performance expressed in instructions per second i.e. 3x10⁹
