FerrFlow Benchmarks

Reusable GitHub Action for FerrFlow performance benchmarks.

Runs the micro and full suites, compares against competing release tools,
and fails the PR when a regression crosses the threshold.

FerrFlow | Fixtures

Usage

- uses: FerrLabs/Benchmarks@v2with:
type: micro # micro, full, or allferrflow-token: ${{ secrets.FERRFLOW_TOKEN }}

Inputs

Input	Description	Default
type	Benchmark type: micro, full, or all	all
skip-competitors	Skip competitor benchmarks in full mode	false
alert-threshold	Regression alert threshold for micro benchmarks (e.g. 120%)	120%
full-regression-threshold	Relative threshold for full benchmark regressions (e.g. 125%)	125%
binary-size-threshold	Binary size growth threshold (e.g. 120%)	120%
comment-on-pr	Post benchmark results as PR comment	true
warmup	Number of warmup runs before timing (hyperfine --warmup)	2
runs	Number of timed runs (hyperfine --runs)	10
definitions	Path to fixture definitions for benchmark generation	required
verbose	Show full error output when a benchmark command fails validation	false
ferrflow-token	GitHub token for PR comments and artifact access	required
group-filter	Criterion bench group filter (substring) for micro matrix sharding	''
binary-dir	Directory holding a prebuilt ferrflow executable. When set, the full benchmark skips its own cargo build --release and puts this directory on PATH	''
fixtures-dir	Directory of already-generated fixtures. When set, the full benchmark skips its own generation	''
shard	Run as a matrix shard: benchmark and write latest.json, skip baseline/compare/comment/uploads	false
merge-partials	Directory of partial latest.json files. When set, skip building and benchmarking; merge the partials, then compare and upload over the merged result	''

Sharding the full benchmark

The full benchmark runs every fixture sequentially, so wall-clock is the sum of them all. To spread it over runners, generate the fixtures once, run one shard per fixture, then aggregate:

1. Shards: one job per fixture, each with shard: true, a fixtures-dir holding only its own fixture, and binary-dir pointing at a prebuilt binary. Each uploads its benchmarks/results/latest.json as a partial.
2. Aggregate: one job that downloads every partial into a directory and passes it as merge-partials. It merges them and runs the regression check, PR comment and uploads once, over the whole result.

Shard per fixture, never per tool: the comparison ferrflow-vs-competitors only means something when both ran on the same machine. Per-fixture shards keep each comparison inside one runner; only absolute numbers between fixtures come from different hardware.

Outputs

Output	Description
regression-detected	true if a performance regression was detected
benchmark-summary	Formatted benchmark summary (markdown) for release notes

Benchmark types

Micro (micro)

Runs criterion benchmarks (cargo bench) and compares against a stored baseline using benchmark-action/github-action-benchmark.

• On PRs: downloads baseline artifact, compares, posts PR comment
• On main push: saves new baseline artifact

Full (full)

Runs end-to-end benchmarks with hyperfine across multiple fixture sizes (single repo, mono-small, mono-medium, mono-large). Optionally compares against competitor tools (semantic-release, changesets, release-please).

• Generates fixtures via the FerrLabs/Fixtures action from the JSON definitions directory you pass
• Measures execution time, memory usage, and binary size
• Compares against stored baseline and detects regressions (configurable threshold, default 25%)

The head-to-head against competitors pins ferrflow --jobs 1. Competing tools are single-threaded, so letting FerrFlow use every core would measure the runner rather than the tool. Parallel speedup is reported separately as ferrflow_parallel alongside runner_cores, and never as the headline number.

Requirements

The calling workflow must provide:

• Rust nightly toolchain (dtolnay/rust-toolchain@nightly)
• Rust cache (Swatinem/rust-cache@v2)
• Node.js (for full benchmarks with competitors): actions/setup-node@v6
• A project with cargo bench --bench ferrflow_benchmarks (for micro)
• A directory of JSON fixture definitions, passed via the definitions input. The action generates the fixtures with FerrLabs/Fixtures (for full)
• A project that builds a release binary with cargo build --release. The action puts target/release on PATH and benchmarks it (for full)