# Linux Kernel Module Cheat

#### 28.3.1. FMA instruction

Fused multiply add:

- x86: Section 29.12.3, “x86 fused multiply add (FMA)”

Bibliography:

- https://en.wikipedia.org/wiki/Multiply–accumulate_operation

- https://en.wikipedia.org/wiki/FMA_instruction_set

Particularly important numerical analysis instruction, that is used in particular for;

- Dot product

- Matrix multiplication

FMA is so important that IEEE 754 specifies it with single precision drop compared to a separate add and multiply!

Micro-op fun: https://stackoverflow.com/questions/28630864/how-is-fma-implemented

Historically, FMA instructions have been added relatively late to instruction sets.