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What are branch misses?
When there is a conditional branch along the way, there are two possible paths that can be followed, and the prefetch unit has no idea which one it should choose, until all the actual condition for that instruction is calculated. The later is called a branch prediction miss, and is also a costly operation.
What will happen if the branch predictor will predict the wrong target?
If it is later detected that the guess was wrong, then the speculatively executed or partially executed instructions are discarded and the pipeline starts over with the correct branch, incurring a delay. Branch prediction is not the same as branch target prediction.
How does branch prediction help in processor performance?
Branch prediction is very important to the performance of a deeply pipelined processor. Branch prediction enables the processor to begin executing instructions long before the branch outcome is certain. Branch delay is the penalty that is incurred in the absence of a correct prediction.
What is bimodal branch prediction?
The most well known technique, referred to here as bimodal branch prediction, makes a prediction based on the direction the branch went the last few times it was executed. More recent work has shown that significantly more accurate predictions can be made by utilizing more branch history.
When a CPU makes branch predictions this is called?
When a CPU makes branch predictions, this is called: static branch prediction.
What are the two types of branch prediction techniques available?
Branch prediction schemes are of two types: static branch schemes and dynamic branch schemes. branch scheme (hardware techniques) is based on the hardware and it assembles the information during the run-time of the program.
What is a disadvantage of static branch prediction?
What is a disadvantage of static branch prediction? Simple implementation. Low branch prediction accuracy (no better than chance). Low branch prediction accuracy (no better than chance).
When an assembler or compiler makes branch predictions this is called?
When an assembler or compiler makes branch predictions, this is called: Static Branch Prediction. When a CPU makes branch predictions, this is called: Dynamic Branch Prediction.