Question 337

Pipeline Depth and Mispredictions

The Pentium 4 had a 20+ stage pipeline while the Pentium Pro had ~14 stages. How does this affect branch misprediction cost?

A

Deeper pipelines eliminate mispredictions entirely through redundant prediction units

B

Deeper pipelines have lower misprediction cost because more instructions can be in flight

C

Pipeline depth has no effect; misprediction cost is determined by branch predictor accuracy alone

D

Deeper pipelines have greater misprediction penalties because more in-flight instructions must be flushed