Question

If a program with 5 instructions is executed in 7 clock cycles, then CPI is ______.
1. 1.4
2. 1.5
3. 1
4. 2

Answer 1

Correct Answer - Option 1 : 1.4

Explanation:

CPI stands for cycles per instructions.

1. It tells the average number of CPU cycles required to retire an instruction, and therefore is an indicator of how much latency in the system affected the running application.

2. Since CPI is a ratio, it will be affected by either change in the number of CPU cycles that an application takes (the numerator) or changes in the number of instructions executed (the denominator). For that reason, CPI is best used for comparison when only one part of the ratio is changing.

\(CPI=\frac{No \ of \ Clock \ Cycles}{No \ of \ Instruction}\)

\(CPI=\frac{7}{5}=1.4\)