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GATE CSE 2021 Set 1 Q63: Time for 100 instructions on a five-stage pipeline

Question

A five-stage pipeline has stage delays of 150, 120, 150, 160 and 140 nanoseconds. The registers that are used between the pipeline stages have a delay of 5 nanoseconds each.

The total time to execute 100 independent instructions on this pipeline, assuming there are no pipeline stalls, is ________ nanoseconds.

Try it: numerical answer: type the value

Numerical answer. No negative marking.
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Answer: 17160 (official GATE 2021 final answer key)

Concept used: Clock period = slowest stage + register delay; nn instructions on a kk-stage pipeline take (k+n−1)(k + n - 1) cycles.

First step: Cycle time =160+5=165= 160 + 5 = 165 ns; the number of cycles is 5+100−15 + 100 - 1.

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Source: official GATE 2021 Set 1 CS question paper and final answer key, organised by IIT Bombay. Question paper · Answer key

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