NIELIT 2017 DEC Scientist B - Section B: 14

Question

We have $10$-stage pipeline, where the branch target conditions are resolved at stage $5$. How many stalls are there for an incorrectly predicted branch?

• A. $5$
• B. $6$
• C. $7$
• D. $4$

Comments

Ans may be 4

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https://gateoverflow.in/182155/pipeline

Answer 1

→ A branch predictor is a digital circuit that tries to guess which way a branch (e.g. an if–then–else structure) will go before this is known definitively.
→ The purpose of the branch predictor is to improve the flow in the instruction pipeline.
→ The technique involves only executing certain instructions if certain predicates are true.
→ Branch prediction is typically implemented in hardware using a branch predictor.
→ Branch target conditions resolved at stage 5 means upto 4 stages there are incorrect branch target conditions are there.
→ So Branch condition is resolved at nth stage means, the number of stalls are (n-1)

Answer will be 4

Answer 2

In branched instr. if target insturction resolved at n stage no. of stall cycle will be (n-1)'

Answer 3

A given that branch occurs at stage 5 , then 4 stages are wasted as we draw the pipeline stage diagram.