Work out branch misprediction penalty instantly with clear inputs, formula shown and shareable results.
A misprediction flushes the pipeline, so the penalty is roughly the pipeline depth in cycles — and on a wide machine that means depth times issue width of lost instruction slots. With 18% branches at 3% misprediction, a 19-stage pipeline loses meaningful performance.
Mispredict cost
CPI added = branch frequency x mispredict rate x pipeline depth
Each flushed cycle discards issue-width instruction slots, so a 4-wide 20-stage machine loses up to 80 instruction slots per mispredict.
TAGE-class predictors reach 98-99% on typical code, but hard-to-predict data-dependent branches remain the main limit on single-thread performance.