Number of stall cycles for given speed up

Question

Anyone? I know my answer is wrong.

Answer 1

Let, Stall_freq = x
$speed\_up = \frac{pipeline\_depth}{1+stall\_freq \times stall\_cycle}$

$3 = \frac{5}{1+x \times 3}$

$3 + 9x = 5$

$x = \frac{2}{9}$

$x = 0.2222$

$x = 22.22 \%$

$\therefore$ 22.22 % instructions have pipeline stalls

Comments

where did you get this reference from? hamacher?

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https://www.cs.umd.edu/class/fall2001/cmsc411/projects/delayedbranch/pipespd.htm