8 - Dynamic Branch Prediction

8 - Dynamic Branch Prediction - Dynamic Branch Prediction...

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Unformatted text preview: Dynamic Branch Prediction The effectiveness of a branch prediction scheme depends on The accurac • The accuracy • The cost of a branch when the prediction is correct and when the prediction is incorrect. Performance = ƒ(accuracy, cost of misprediction) These branch penalties depend on • the structure of the pipeline, • the type of predictor, • and the strategies used for recovering from misprediction. The simplest dynamic branch-prediction scheme is • a branch-prediction buffer or branch history table. h It is a small memory indexed by the lower portion of the address of the branch instruction h It is a small memory indexed by the lower portion of the address of the branch instruction h it has no tags and is useful only to reduce the branch delay when it is longer than the time to compute the possible target PCs. h If the hint turns out to be wrong, the prediction bit is inverted and stored back. Branch History Table is simplest – Lower bits of PC address index table of 1-bit value...
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This note was uploaded on 01/21/2012 for the course CSCI 593 taught by Professor Hamnes during the Spring '11 term at St. Cloud.

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8 - Dynamic Branch Prediction - Dynamic Branch Prediction...

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