perf.yml

name: perf

# Records usage's startup cost for every commit that lands on main, into the
# git-notes ref `refs/notes/tak`. The data lives in this repository — there is
# no external service holding it, and `git fetch origin refs/notes/tak:refs/notes/tak`
# gets you the whole history.
#
# Only runs post-merge. A PR-time gate is the eventual goal, but a gate needs a
# baseline series to compare against, and right now there is none. This builds
# that baseline.

on:
  push:
    branches: ["main"]
  workflow_dispatch:

permissions: {}

# Never two at once. Concurrent runs race the notes push; tak retries with a
# cat_sort_uniq merge so nothing is lost, but serialising avoids the churn.
# cancel-in-progress is off deliberately: every commit gets a measurement, and
# a cancelled run is a hole in the series.
concurrency:
  group: perf
  cancel-in-progress: false

env:
  MBX_DISABLE: "1"
  CARGO_TERM_COLOR: always
  CARGO_INCREMENTAL: "0"
  TAK_RUNNER: jdx-perf-v1-ubuntu24.04-x64-usage-rust1.97.1-img5263c143

jobs:
  measure:
    name: Measure
    # Pinned to one runner class on purpose. Absolute instruction counts shift
    # between machine types by more than a real regression does, so a series
    # that wanders between runners is unreadable.
    runs-on: [self-hosted, jdx-perf-v1]
    container:
      image: ghcr.io/jdx/perf-runner:jdx-perf-v1@sha256:5263c143b12ce2234e7b0b21d3d6501c2ed05837b42937d0eaeaa191cd5c8e68
      options: --cpuset-cpus 0-7
    timeout-minutes: 30
    permissions:
      contents: read
    steps:
      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          persist-credentials: false

      # Compile inside the pinned job container. Restoring target/ could relabel
      # a binary built on another runner class as a jdx-perf-v1 measurement.
      - uses: jdx/mise-action@2d8d4cafcbd33be2ea37d2b6f5ad595363d1f1ca # v5.1.1
        with:
          cache: false
        env:
          MISE_LOCKED: "1"

      # cachegrind is the whole point: it counts instructions, which reproduce
      # to ~0.02% run-to-run where wall clock on this same hardware moves by
      # 4-20%. Without it tak still records timing, but the series stops being
      # precise enough to detect anything.
      - name: Install valgrind
        timeout-minutes: 3
        run: |
          command -v valgrind || {
            sudo apt-get update
            sudo apt-get install -y --no-install-recommends valgrind
          }
          valgrind --version

      - name: Runner metadata
        run: |
          {
            echo '### Runner metadata'
            echo '```text'
            echo 'environment-revision: perf-runner@fd66d9b'
            echo 'image: ghcr.io/jdx/perf-runner@sha256:5263c143b12ce2234e7b0b21d3d6501c2ed05837b42937d0eaeaa191cd5c8e68'
            uname -a
            lscpu
            mise --version
            rustc --version
            cargo --version
            valgrind --version
            for zone in /sys/class/thermal/thermal_zone*/temp; do
              [ -r "$zone" ] && printf '%s: %s\n' "$zone" "$(cat "$zone")"
            done
            echo '```'
          } >> "$GITHUB_STEP_SUMMARY"

      - name: Measure and record
        run: |
          taskset -c 0-3 mise run perf:record
      - name: Package measurement note
        if: github.ref == 'refs/heads/main'
        run: |
          mkdir -p /tmp/tak-out
          git notes --ref=tak show HEAD > /tmp/tak-out/note
          git rev-parse HEAD > /tmp/tak-out/sha

      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
        if: github.ref == 'refs/heads/main'
        with:
          name: tak-measurement
          path: /tmp/tak-out
          retention-days: 1
          if-no-files-found: error

      - name: Summary
        run: tak history >> "$GITHUB_STEP_SUMMARY"

  publish:
    name: Publish measurement note
    needs: measure
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    timeout-minutes: 10
    permissions:
      contents: write
    steps:
      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
        with:
          name: tak-measurement
          path: /tmp/tak-out

      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
        with:
          fetch-depth: 0
          persist-credentials: false

      - name: Publish refs/notes/tak
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          REPOSITORY: ${{ github.repository }}
        run: |
          set -o pipefail
          sha=$(cat /tmp/tak-out/sha)
          git config user.name "github-actions[bot]"
          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
          git fetch origin +refs/notes/tak:refs/notes/tak-remote || true
          if git rev-parse --verify --quiet refs/notes/tak-remote >/dev/null; then
            git update-ref refs/notes/tak refs/notes/tak-remote
          fi
          {
            git notes --ref=tak show "$sha" 2>/dev/null || true
            cat /tmp/tak-out/note
          } | LC_ALL=C sort -u > /tmp/tak-out/merged-note
          git notes --ref=tak add -f -F /tmp/tak-out/merged-note "$sha"

          remote="https://x-access-token:${GITHUB_TOKEN}@github.com/${REPOSITORY}.git"
          for attempt in 1 2 3 4 5; do
            if git push --quiet "$remote" refs/notes/tak:refs/notes/tak; then
              exit 0
            fi
            if [ "$attempt" -eq 5 ]; then
              echo "::error::could not publish refs/notes/tak after five attempts"
              exit 1
            fi
            git fetch --quiet "$remote" +refs/notes/tak:refs/notes/tak-remote
            git notes --ref=tak merge -s cat_sort_uniq refs/notes/tak-remote
          done