From 692098fdb922c464949fad7c5b9e36b531ea6f68 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Mon, 2 Oct 2023 10:49:41 -0400
Subject: bench: Add a README

---
 bench/README.md | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 bench/README.md

(limited to 'bench')

diff --git a/bench/README.md b/bench/README.md
new file mode 100644
index 0000000..56157a0
--- /dev/null
+++ b/bench/README.md
@@ -0,0 +1,51 @@
+This directory contains a suite of benchmarks used to evaluate `bfs` and detect performance regressions.
+To run them, you'll need the [tailfin] benchmark harness.
+You can read the full usage information with
+
+[tailfin]: https://github.com/tavianator/tailfin
+
+```console
+$ tailfin -n run bench/bench.sh --help
+Usage: tailfin run bench/bench.sh [--default]
+           [--complete] [--early-quit] [--print] [--strategies]
+           [--build=...] [--bfs] [--find] [--fd]
+           [--no-clean] [--help]
+...
+```
+
+The benchmarks use various git repositories to have a realistic and reproducible directory structure as a corpus.
+Currently, those are the [Linux], [Rust], and [Chromium] repos.
+The scripts will automatically clone those repos using [partial clone] filters to avoid downloading the actual file contents, saving bandwidth and space.
+
+[Linux]: https://github.com/torvalds/linux.git
+[Rust]: https://github.com/rust-lang/rust.git
+[Chromium]: https://chromium.googlesource.com/chromium/src.git
+[partial clone]: https://git-scm.com/docs/partial-clone
+
+You can try out a quick benchmark by running
+
+```console
+$ tailfin run bench/bench.sh --build=main --complete=linux
+```
+
+This will build the `main` branch, and measure the complete traversal of the Linux repo.
+Results will be both printed to the console and saved in a Markdown file, which you can find by running
+
+```console
+$ tailfin latest
+results/2023/09/29/15:32:49
+$ cat results/2023/09/29/15:32:49/runs/1/bench.md
+## Complete traversal
+...
+```
+
+To measure performance improvements/regressions of a change, compare the `main` branch to the topic branch on the full benchmark suite:
+
+```console
+$ tailfin run bench/bench.sh --build=main --build=branch --default
+```
+
+This will take a few minutes.
+Results from the full benchmark suite can be seen in performance-related pull requests, for example [#126].
+
+[#126]: https://github.com/tavianator/bfs/pull/126
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