branch prediction
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branch prediction
[′branch prə‚dik·shən] (computer science)
A method whereby a processor guesses the outcome of a branch instruction so that it can prepare in advance to carry out the instructions that follow the predicted outcome.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
branch prediction
(processor, algorithm)A technique used in some processors
with instruction prefetch to guess whether a conditional branch will be taken or not and prefetch code from the
appropriate location.
When a branch instruction is executed, its address and that of the next instruction executed (the chosen destination of the branch) are stored in the Branch Target Buffer. This information is used to predict which way the instruction will branch the next time it is executed so that instruction prefetch can continue. When the prediction is correct (and it is over 90% of the time), executing a branch does not cause a pipeline break.
Some later CPUs simply prefetch both paths instead of trying to predict which way the branch will go.
An extension of the idea of branch prediction is speculative execution.
When a branch instruction is executed, its address and that of the next instruction executed (the chosen destination of the branch) are stored in the Branch Target Buffer. This information is used to predict which way the instruction will branch the next time it is executed so that instruction prefetch can continue. When the prediction is correct (and it is over 90% of the time), executing a branch does not cause a pipeline break.
Some later CPUs simply prefetch both paths instead of trying to predict which way the branch will go.
An extension of the idea of branch prediction is speculative execution.
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)
branch prediction
In CPU instruction execution, predicting the outcome of a branch so that those instructions may be executed in parallel with the current instructions. If the CPU guesses the wrong branch, it will take extra machine cycles to go back and execute the correct one; however, on average, if the prediction algorithms are good, overall performance is increased. See predication and branch.Copyright © 1981-2019 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.