GATE 2014 CS (CS1) – Question 65

Computer Organization and Architecture · Instruction Set and Addressing Modes · 2 marks · Numerical answer

Processors P₁ and P₂ execute the same instruction set. Under identical conditions and input, P₂ takes 25% less time but incurs 20% more CPI than P₁. P₁ runs at 1 GHz. Find P₂ clock frequency (GHz).

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Correct answer: 1.6 to 1.6

Explanation

Execution time is instruction count×CPI/frequency. With the same instruction count,0.75=T₂/T₁=1.2f₁/f₂. Therefore f₂=1.2/0.75×1GHz=**1.6GHz**. Higher CPI requires a proportionally larger frequency increase to achieve the lower time.