Branch misprediction
Encyclopedia
Branch misprediction occurs when a central processing unit
(CPU) mispredicts the next instruction to process in branch prediction, which is aimed at speeding up execution.
During the execution of certain programs there are places where the program execution flow can continue in several ways. These are called branch
es, or conditional jumps. The CPU also uses a pipeline which allows several instructions to be processed at the same time. When the code for a conditional jump is read we do not yet know the next instruction to execute and insert into the execution pipeline. This is where branch prediction comes in.
Branch prediction guesses the next instruction to execute and inserts the next assumed instruction to the pipeline. Guessing wrong is called branch misprediction. The partially processed instructions in the pipeline after the branch have to be discarded and the pipeline has to start over at the correct branch when a branch misprediction is detected. This slows down the program execution.
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
(CPU) mispredicts the next instruction to process in branch prediction, which is aimed at speeding up execution.
During the execution of certain programs there are places where the program execution flow can continue in several ways. These are called branch
Branch (computer science)
A branch is sequence of code in a computer program which is conditionally executed depending on whether the flow of control is altered or not . The term can be used when referring to programs in high level languages as well as program written in machine code or assembly language...
es, or conditional jumps. The CPU also uses a pipeline which allows several instructions to be processed at the same time. When the code for a conditional jump is read we do not yet know the next instruction to execute and insert into the execution pipeline. This is where branch prediction comes in.
Branch prediction guesses the next instruction to execute and inserts the next assumed instruction to the pipeline. Guessing wrong is called branch misprediction. The partially processed instructions in the pipeline after the branch have to be discarded and the pipeline has to start over at the correct branch when a branch misprediction is detected. This slows down the program execution.