# matmul-bench

Compares matrix-matrix multiply (GEMM) performance across implementations
running in the browser, plus a native reference measured outside it.

**Live:** https://concept-collection.github.io/matmul-bench/

Methods:

- **JavaScript/TypeScript** — plain triple loop over `Float64Array` (f64), no
  special-casing. The "no special effort" baseline.
- **WebGPU** — a tiled compute shader (f32; WGSL has no double precision).
- **WASM from custom C** — naive, blocked+SIMD (`f64x2`, `-msimd128`), and a
  threaded (WASM pthreads) version of the blocked+SIMD kernel, built with
  emscripten (f64). The threaded one needs cross-origin isolation.
- **libFLAME/BLIS in WASM** — a real BLAS (`dgemm` via libFLAME + BLIS)
  compiled to WebAssembly, single-threaded and multi-threaded (WASM pthreads),
  from [libflame2wasm](https://github.com/magland/libflame2wasm) (f64). The
  threaded build needs cross-origin isolation (SharedArrayBuffer), supplied on
  GitHub Pages by a vendored service worker.
- **Native LAPACK/OpenBLAS** — a fixed reference table from `dgemm` run
  outside the browser (`native/`).

## Develop

```bash
npm install
npm run dev            # local dev server (sends COOP/COEP for threaded methods)
wasm/build-wasm.sh      # rebuild wasm/dist/matmul.* + public/matmul/matmul_mt.*
                        #   (needs emsdk)
blis/build-blis-wasm.sh # rebuild public/matmul/matmul_blis_{st,mt}.* (needs emsdk
                        #   + the prebuilt .a files from a sibling libflame2wasm)
npm run build           # tsc -b && vite build
```

The libFLAME/BLIS WASM artifacts under `public/matmul/` are committed (they link
~30 MB of prebuilt static libraries that live in a separate
[libflame2wasm](https://github.com/magland/libflame2wasm) checkout), so the
GitHub Pages build doesn't rebuild them. The threaded custom module
(`public/matmul/matmul_mt.*`) is built in CI from `wasm/matmul.c`.

## Native reference

```bash
native/build.sh
OPENBLAS_NUM_THREADS=1  native/bench_native 128 256 512 1024 2048
OPENBLAS_NUM_THREADS=12 native/bench_native 128 256 512 1024 2048
```

Hand-copy the results into `src/data/nativeReference.ts`.