Pipeline performance / cost ratio.

Question

The time taken to execute a program on a non-pipelined machine is t. The same program is then executed on an m stage pipeline. The cost of all the logic stages of the pipeline is given by c and h is the cost of each latch. The delay incurred by each pipeline stage is d.

What is the expression for pipeline performance/cost ratio?

1. (mc + m2h)/(t + m2d)

2. (mc + m2h)/(t + md)

3. m/(ct + mht + m2cd + m3dh)

4. m/(ct + ht + mcd + m2dh)

Answer 1

Execution time on non-pipelined machine=t

Execution time on m-stage pipelined machine=t/m+dm

Performance(P)= 1/(t/m+dm) =m/(t+dm2)

Cost of pipeline stage is given by

Cost(C)=c+mh

Performance/Cost ratio = m/(t+dm2) /(c+mh)

                                      = m/(ct+mht+m2cd+m3dh)

So option(3) is the correct answer

Comments

i think performance or throughput wil be =  1/(t/m + d)