Implementation of a confidence estimator
Information from the branch prediction tables is used:
- Use of saturation counter information to construct a confidence estimator ? speculate more aggressively when the confidence level is higher
- Used of a miss distance counter table (MDC): ? Each time a branch is predicted, the value in the MDC is compared to a threshold. If the value is above the threshold, then the branch is considered to have high confidence, and low confidence otherwise.
- A small number of branch history patterns typically leads to correct predictions in a PAs predictor scheme. The confidence estimator assigned high confidence to a fixed set of patterns and low confidence to all others.
Confidence estimation can be used for speculation control,thread switching in multithreaded processors or multipath execution