A five-stage pipeline has stage delays of 150,120,150,160 and 140 nanoseconds.…
2021
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.
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Correct answer: 17160
Key idea: the pipeline cycle time is the slowest stage plus the register delay; total time for n instructions in an m-stage pipeline is (m + n - 1) cycles × cycle time.
Cycle time = max(stage delays) + register delay = 160 ns + 5 ns = 165 ns.
Number of cycles to finish 100 instructions = number of stages + number of instructions - 1 = 5 + 100 - 1 = 104 cycles.
Total time = 104 × 165 ns = 17,160 ns.
Final answer: 17160 nanoseconds.
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