GATE 2016 CS (CS2) – Question 40

Computer Organization and Architecture · Instruction Pipelining and Pipeline Hazards · 2 marks · Numerical answer

F takes 5 ns and G takes 3 ns on their functional units. Two instances of each unit are available. Ignoring other delays, find the minimum time for F(G(Xᵢ)), 1 ≤ i ≤ 10, in ns.

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Correct answer: 28.0 to 28.0

Explanation

The first two G results arrive after 3 ns. The two F units must then process five pairs at 5 ns per pair. G can prepare later pairs while F works and is never the bottleneck. The lower bound 3+5×5=28 ns is therefore attained.

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