SIMD and Go
A practical, CPU-level introduction to SIMD that shows how Go's experimental vector APIs can express hot loops in ordinary Go, while making the hardware, portability, and measurement trade-offs concrete.
Logged at IST: 2026-10-20
What it is: Jesús Espino's hands-on introduction to SIMD (Single Instruction, Multiple Data) and Go's experimental simd/archsimd and portable simd packages.
Gist: SIMD lets one CPU instruction apply the same operation to several values in parallel. The article develops the mental model from vector registers and lanes through the usual load–operate–store cycle, then walks through vector operations, masks, permutations, partial loads, and a dot-product example in Go.
The examples use Go 1.27.0 with GOEXPERIMENT=simd and focus on amd64. simd/archsimd exposes architecture-specific vector types and operations; the portable simd package builds on this with size-agnostic code and runtime selection. The author reports that the example dot product ran about 9× faster than a plain loop on his machine, while emphasizing that the gain depends on the problem and data, and that the APIs remain experimental. Benchmark and profile before keeping SIMD code: it adds complexity and is not automatically faster for every workload.
Why it matters: A clear bridge between the abstract promise of Go's SIMD experiment and the practical details of writing vectorized code: lanes, tails, CPU support, and the cost of giving up straightforward scalar code.
Source: https://internals-for-interns.com/posts/go-simd/ Go SIMD design context: https://go.dev/blog/simd-experiment Saved X post: https://x.com/jespinog/status/2112249421886800028