Consider a 3-stage pipelined processor having a delay of 10 ns (nanoseconds),…
2023
Consider a 3-stage pipelined processor having a delay of 10 ns (nanoseconds), 20 ns, and 14 ns, for the first, second, and the third stages, respectively. Assume that there is no other delay and the processor does not suffer from any pipeline hazards. Also assume that one instruction is fetched every cycle.
The total execution time for executing 100 instructions on this processor is ns ________.
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Correct answer: 2040
Key idea: the pipeline clock period is determined by the slowest stage, and a k-stage pipeline requires (k − 1) extra cycles to fill before steady state is reached.
Stage delays: 10 ns, 20 ns, and 14 ns → cycle time = max(10, 20, 14) = 20 ns.
Pipeline depth k = 3 → startup overhead = k − 1 = 2 cycles.
Total cycles for 100 instructions = 100 + 2 = 102 cycles.
Total execution time = 102 cycles × 20 ns/cycle = 2040 ns.
Answer: 2040 ns.