Geeksforgeeks MOCK II COA

Question

Can anyone solve this??
Doubts: Branch penalty should be 2. right?
and what is the branch penalty for unconditional branch?

Comments

Branch penalty should be 2. right?

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Each stage takes 4 cycles so penalty should (3-1)×4 cycles.

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Someone plz explain when each stage is taking 4 cycles, we cannot take CPI as 1. Is that correct??? If large no. Of instructions were there then it would be 4.

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Can anyone solve whole question?

I am not getting this.

Answer 1

Branch penalty is 2 ,beacuse the target address we are getting in 3rd stage.

80% are unconditional branches , ie we have to jump there , and there is no time needed to calculate the target address.

// ie. no stalls.

For 20%, the branch penaly is 2.

Speed Up = No. of stages/ (1+ (branch penalty)*(% of conditional branch instructions))

=4/(1+2*0.2)=2.857=2.86

// Here we are ignoring the cases, where branch is not taken. We are assuming for all 20% conditional instrustions, branch is taken.

Comments

ok!!

just to get know.

what is the penalty for condition branch and branch is not taken?