Assume that each of the above steps takes the amount of time specified in the ta
ID: 3775826 • Letter: A
Question
Assume that each of the above steps takes the amount of time specified in the table below. Fetch 300 ps Decode 100 ps Execute 200 ps Memory 350 ps Writeback 100 ps Assume that the latency of pipeline registers is 50 ps A Given the limes for the data-path stages listed above, what is the clock frequency for the non-pipelined and pipelined data-paths B Assuming no hazards or stalls, what is the ideal pipeline speedup? C If we can extend the pipelined data-path to 10 stages, how would you allocate the additional pipeline stages D. In ideal condition (no hazard and stall), Calculate achievable speedup of the 10-stage pipelined data path against the classic 5-stage pipelined data-pathExplanation / Answer
There are multiple parts of this question. I will answer the first one.
5
A)
for the non-pipelined data path time taken for each instruction will be the sum of all the stages =
300+100+200+350+100 = 1050 ps
frequency will be 1/time period = 952380000 Hz or 952 Mhz
for the pipelined processor the time taken for each instruction will be equal to the longest stage in the pipeline plus the register time.
350+50=400 ps
frequency will be 1/400 = 2,500,000,000 Hz or 2.5 Ghz
b)
The ideal speed up is given by
time taken in unpipelined processor/ number of pipe stages = 1050/5 = 210
c)
Ideally I would like to divide the longest time consuming path in the pipeline so that throughtput can be increased.
Since now the length of the pipe is doubled 10 stages we have extra 5 stages.
Fetch I will divide into 3 stages so that it takes 100 100 100 ns
Execute I will divide into 2 stages so that it takes 100 100 ns
Memory I will divide into 3 stages so that it takes 118 116 116 ns
so the pipeline will be
Fetch1 - 100 ps
Fetch 2 - 100ps
Fetch 3 - 100ps
Decode - 100 ps
Execute 1 - 100 ps
Execute 2 - 100 ps
Memory 1 - 116 ps
Memory 2 - 116 ps
Memory 3 - 118 ps
Writeback - 100 ps
D)
Speed up in 10 stage pipeline will be 1050/10 = 105
compared to 5 stage it will be 2x faster.