Branch Prediction on the G4e and Pentium 4

The G4e and the Pentium 4 each use both static and dynamic branch prediction techniques to prevent mispredictions and branch delays. If a branch instruction does not have an entry in the BHT, both processors will use static prediction to decide which path to take. If the instruction does have a BHT entry, dynamic prediction is used. The Pentium 4’s BHT is quite large; at 4,000 entries, it has enough space to store information on most of the branches in an average program.

The earlier PIII’s branch predictor had a success rate of around 91 percent, and the Pentium 4 allegedly uses an even more advanced algorithm to predict branches, so it should perform even better. The Pentium 4 also uses a BTB to store ...

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