# Execution time of a linear pipeline

1. A simple linear pipeline has three stages. The execution times in the stages are 10, 15, and 12 units respectively. If the pipeline is used to process 100 inputs, then the execution time is

(a) 1530 units

(b) 3700 units

(c) 1500 units

(d) 1537 units

I am not able to understand this question. can anyone help me to understand this question and also the solution.

• This question looks very basic. If you cannot understand it, I suggest you review the material. – Yuval Filmus May 19 '17 at 7:54

## 1 Answer

Every input ("job", "task", whatever) must be processed by all three pipeline stages. The respective execution times for each stage are given; they are the same for each input.

If there are no other inputs (imagine an empty system), a single input will leave the pipeline after 10+15+12 time units, right?

But if there is more than only one input, you might have to deal with congestion... that's what this question is all about. So, how long does it take until the last of the 100 inputs has left the pipeline?

(But I'm not giving out solutions here...)