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In computer engineering, out-of-order execution (or more formally dynamic execution) is a paradigm used in high-performance central processing units to make use of instruction cycles that would otherwise be wasted.
L'exécution dans le désordre (« out of order execution » en anglais) consiste à réorganiser l'ordre dans lequel les instructions vont s'exécuter dans le processeur. Ces instructions ne sont alors pas forcément exécutées dans l'ordre dans lequel elles apparaissent dans le programme [1].
Renaming and Out-of-order execution was first implemented in 1969 in IBM 360/91 but did not show up in the subsequent models until mid-Nineties. Why ? Reasons 1. Exceptions not precise! 2. Effective on a very small class of programs One more problem needed to be solved Control transfers October 24, 2005
Out-of-order instruction execution. instructions are fetched in compiler-generated order. instruction completion may be in-order (today) or out-of-order (older computers) in between they may be executed in some other order. independent instructions behind a stalled instruction can pass it. instructions are dynamically scheduled.
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3 déc. 2021 · An in-order implementation would just stall until the data becomes available, whereas an out of order implementation can (provided there are instructions ahead that can't be executed independently) get something else done while the processor waits for the data to be delivered from memory.
- That's pretty much it. Out-of-order execution "greedily" executes every instruction it can as quickly as possible without waiting for previous inst...
- The architecture has little to do with it, in ARM one of the more significant differences is memory ordering can be quite relaxed (possibly under t...
- It could also be mentioned that out of order executing proccessors have a "window" over the incoming units of bytes instructions. It comes naturall...
Renaming and Out-of-order execution was first implemented in 1969 in IBM 360/91 but was effective only on a very small class of problems and thus did not show up in the subsequent models until mid-nineties. Why? 1. Did not address the memory latency problem which turned out be a much bigger issue than FU latency 2. Made exceptions imprecise
Out-of-Order Execution. In order to enhance performance and parallelize a program, which is by construct sequential, modern processors execute instructions from different parts of the program in parallel. It may happen that one instruction being executed is preceded by a set of instructions, which are yet to execute.
