The stage delays in a 4-stage pipeline are 800, 500, 400 and 300 picoseconds.…
2016
The stage delays in a 4-stage pipeline are 800, 500, 400 and 300 picoseconds. The first stage (with delay 800 picoseconds) is replaced with a functionally equivalent design involving two stages with respective delays 600 and 350 picoseconds. The throughput increase of the pipeline is ________ percent.
Attempted by 112 students.
Show answer & explanation
Correct answer: 33.33
Key idea: pipeline throughput is inversely proportional to the clock period, and the clock period is set by the maximum stage delay.
Original pipeline max stage delay = 800 ps, so original clock period = 800 ps and original throughput ∝ 1/800.
After replacing the first stage by two stages, the stage delays are 600, 350, 500, 400, 300 ps; the new max delay = 600 ps, so new clock period = 600 ps and new throughput ∝ 1/600.
Percent increase = ((1/600) - (1/800)) / (1/800) × 100% = (1/2400) / (1/800) × 100% = (1/3) × 100% ≈ 33.33%.
Answer: The throughput increases by approximately 33.33% (≈33%).
A video solution is available for this question — log in and enroll to watch it.