What is the time required to execute program without branch prediction ?

Question

Program consists of 16 instructions (I₁, I₂, I₃, ...., I₁₆). In which I₆ is a unconditional branch instruction transfer the controls of I₁₂. In the pipeline, branch target address will be available at the end of execute state. Each instruction spends the same amount of time in all the pipeline stages. The cycle time of the pipeline is 10 nsec.

What is the time (in nsec) required to execute the above program without using branch prediction?

Answer 1

Let there be four stages
S1 = Instruction fetch
S2 = Instruction decode
S3 = Execute
S4 = Write back

Using (K+n-1)tp
1. I1 to I6 execute first
2. I7 & I8 will also be executed at this point I6 will reach to execute stage so it sends the control to I12
3.I12 to 116  will execute

so total 13 instruction
(13-1+4)10 = 160ns

Comments

Answer given was 170, but can you draw the Instruction pipeline diagram.

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In the ques 5 stage pipeline execution applied!!

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yeah for 4 stage ans should be 160,and 5 stage 170...