AVX-512
How it works
AVX-512 operates on 32 ZMM registers 512 bits wide, holding e.g. 16 float32 or 8 float64 values. The new EVEX encoding expands the operand space and adds per-instruction masking: eight mask registers (k0โk7) select which vector elements are processed or blended, removing some branching. FMA instructions fuse a multiply and an add in one cycle, and embedded broadcast lets a scalar value from memory serve as a vector operand. The AI subsets work on quantized data: VNNI performs INT8/INT16 multiply-accumulate in single instructions (key for the dot products in GEMM), while BF16 and FP16 accelerate reduced-precision compute. Thanks to the VL extension, the same operations can also run on 128- and 256-bit registers.
Problem solved
Numerical compute and ML model inference on CPU are limited by vector-unit throughput. Twice-wider vectors (512 vs 256 bits in AVX2), more registers and FMA/VNNI-type instructions let the CPU perform more multiply-accumulate operations per cycle, accelerating GEMM, dot products and neural-network layers without a dedicated accelerator.
Components
32 vector registers 512 bits wide (up from 16 in AVX2). Hold e.g. 16ร float32, 8ร float64, 64ร int8.
Eight opmask registers (k0โk7) that conditionally process or blend individual vector elements without branching.
A new encoding prefix (successor to VEX) enabling 32-register addressing, masking, embedded broadcast and embedded rounding/exception control.
The base subset required in all AVX-512 implementations; extends most 32/64-bit instructions to 512-bit registers, including FMA.
Vector Neural Network Instructions (Cascade Lake, 2019) โ integer (INT8/INT16) multiply-accumulate in single instructions, key for quantized inference.
AI-acceleration instructions operating on the bfloat16 format (Cooper Lake, 2020).
Extends F16C with comprehensive support for binary16 (FP16/half-precision) numbers (Sapphire Rapids, 2023).
Evolution
Intel proposes the 512-bit SIMD extensions to the x86 architecture (July 2013).
First hardware implementation in the Intel Xeon Phi x200 (Knights Landing) with the F, CD, ER, PF subsets.
AVX-512 enters mainstream server/workstation CPUs (Xeon Scalable "Purley"), adding the VL, DQ, BW subsets.
Introduction of Vector Neural Network Instructions to accelerate quantized (INT8) inference.
Addition of AI-acceleration instructions operating on the bfloat16 format.
AMD implements AVX-512 (F, CD, VL, DQ, BW, IFMA, VBMI, VNNI, BF16 and others) in the Zen 4 microarchitecture.
Sapphire Rapids adds the FP16 subset; Intel announces the successor โ AVX10 (July 2023).
Execution paradigm
SIMD: a single instruction operates densely on many data elements in a vector register; k0โk7 masks provide conditional per-element execution.
Parallelism
Data-level parallelism (SIMD) โ one instruction processes up to 16 float32 / 64 int8 at once within a CPU core.
Hardware requirements
AVX-512 is an x86 instruction-set extension executed natively by CPU vector units (Intel since Knights Landing/Skylake-X, AMD since Zen 4).