Editing Speedup (section)

===Using cycles per instruction and instructions per cycle===
We can also measure speedup in cycles per instruction (CPI) which is a latency. First, we execute the program with the standard branch predictor, which yields a CPI of 3. Next, we execute the program with our modified branch predictor, which yields a CPI of 2. In both cases the execution workload is the same and both architectures are not pipelined nor parallel. Using the speedup formula gives
: <math>S_\text{latency} = \frac{L_\text{old}}{L_\text{new}} = \frac{3~\text{CPI}}{2~\text{CPI}} = 1.5.</math>

We can also measure speedup in instructions per cycle ([[Instructions per cycle|IPC]]), which is a throughput and the inverse of CPI. Using the speedup formula gives
: <math>S_\text{throughput} = \frac{Q_\text{new}}{Q_\text{old}} = \frac{0.5~\text{IPC}}{0.33~\text{IPC}} = 1.5.</math>

We achieve the same 1.5x speedup, though we measured different quantities.