Given a pipeline A of five stages where each stage takes tim

Given a pipeline, A, of five stages, where each stage takes time t, produce a new pipeline, B, by dividing the third stage into two stages such that each stage takes time t/2. How many instructions per second does pipeline A complete per second? pipeline B? Explain.

Solution

So Given a pipeline having five stages and we are deviding the third pipeline into two halves

First of all why do we need to split a stage, to reduce the cycle time

Here it takes \'t\' seconds to run 1 instruction per cycle

So if we split the 3rd stage into 2 halves throughput will increase

if we calculate latency for five stages it will be 5*(cycle time)

for example:

3^rd stage Memory. New CT = 520ps

3^rd stage Fetch. New CT = 260ps

The new latency is 6(cycle time), since an instruction needs to go through 6 pipeline stages now.

But throughput for both is still 1 instruction/cycle. Throughput increases because the cycle time reduces.