A computer has the following CPIs for instruction types A, B, C, D, and a program P3 has the following mix of instructions,

INSTRUCTION TYPE Cycle per Instruction FREQUENCY
A 1.7 22%
B 2.1 29%
C 2.7 17%
D 2.4 32%

What will be the average CPI for given above system?
(A) 2.21
(B) 3.6
(C) 1.57
(D) 2.4


Answer: (A)

Explanation: Average cycle per instruction (CPI),

= Σ(CPIi * ICi) 
= (1.7 * 0.22 + 2.1 * 0.29 + 2.7 * 0.17 + 2.4 * 0.32) 
= 2.21 

SO, option (A) is correct.


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  • Last Updated : 02 Jan, 2019

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