Andrew S. Tanenbaum (OS) Edition 4 Exercise 1 Question 14 (Page No. 82)

Question

A computer has a pipeline with four stages. Each stage takes the same time to do its work, namely, $1$ nsec. How many instructions per second can this machine execute?

Comments

Lakshman Patel RJIT

what is the answer ??

Is it $10^{9}$ or  $\frac{n}{n+3}*10^{9}$

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i think 10^9 is right answer

Answer 1

Is this correct?
Since we want to see how many instructions (n, say) can be executed in 1 second

(n+3)*10^(-9) = 1

Thus, n = (10^9) - 3

Answer 2

1 Instn -----> 4nsec

so, In 1sec -------> 25 *10^7 Instn

Answer 3

total four stages.

each stage takes 1 nano second, so four stages take 4 ns.

so we can say one instruction takes 4 ns.

hence in one second total nos of instructions executed=1/4 ns=1/4*10^-9=(1/4)*10^9=25*10^7 nos.

Answer 4

Tp= 1ns
Throughput=1/Tp        instruction per second
Throughput= 1/10^-9 =1000 MIPS