Pipeline Stall

Question

I am very Confused in determining the number of stalls in a given execution. Please determine how to find out the number of stalls in the execution of the pipeline.

Like In this example calculate the number of stalls:- 

I successfully calculated the total clock cycle but plz indicate number of stalls and where it took place ?

Instruction	Fetch	Decode	Execute	Write
1	1	2	2	1
2	2	3	3	2
3	3	1	1	1
4	1	1	1	1

Comments

yes, I am also getting the same

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i m confused here shouldn’t  stalls = number of cycle wasted insrtead of number of slots wasted

so answer will be 7

Answer 1

 bubble or pipeline stall is a delay in execution of an instruction in an instruction pipeline

Comments

Sir i said 2 because when we do add instruction then what i usually consider is that after writing the value of Ro (in above case) its then saved back into memory and in succeeding instructions i fetch that value i.e. Ro first and do remaining operation

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Sir please help me out here

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@ abhishekmehta4u i think 9 stalls will be there because  $I_4's$ first stall is already counted in $I_3$.