Publish benchmark history and dashboard

.github/workflows/benchmark.yml

@@ -0,0 +1,43 @@
+name: Benchmarks
+
+on:
+    push:
+        branches: [main]
+    schedule:
+        - cron: "0 4 * * 1"
+    workflow_dispatch:
+
+concurrency:
+    group: benchmark-results
+    cancel-in-progress: false
+
+jobs:
+    benchmark:
+        runs-on: ubuntu-latest
+        permissions:
+            contents: write
+        steps:
+            - uses: actions/checkout@v7
+
+            - name: Install build dependencies
+              run: ./scripts/build-dependencies.sh
+
+            - name: Build and run benchmarks
+              working-directory: ctprintf
+              run: |
+                  cmake --workflow --fresh --preset benchmark-workflow
+                  ./build/benchmark/benchmarks/ctprintf_benchmarks \
+                      --benchmark_min_time=1s \
+                      --benchmark_repetitions=3 \
+                      --benchmark_out=./build/benchmark/benchmarks/benchmark_results.json \
+                      --benchmark_out_format=json
+
+            - name: Publish benchmark results
+              uses: benchmark-action/github-action-benchmark@d48d326b4ca9ba73ca0cd0d59f108f9e02a381c7
+              with:
+                  tool: googlecpp
+                  output-file-path: ctprintf/build/benchmark/benchmarks/benchmark_results.json
+                  github-token: ${{ secrets.GITHUB_TOKEN }}
+                  gh-pages-branch: gh-pages
+                  benchmark-data-dir-path: dev/bench
+                  auto-push: true

.github/workflows/ci-build.yml

@@ -35,14 +35,6 @@ jobs:
               working-directory: ctprintf
               run: cmake --workflow --preset release-workflow
 
-            - name: Run performance benchmarks
-              working-directory: ctprintf
-              run: |
-                  cmake --workflow --fresh --preset benchmark-workflow
-                  ./build/benchmark/benchmarks/ctprintf_benchmarks \
-                      --benchmark_min_time=1s \
-                      --benchmark_repetitions=3
-
             - name: Build Debian package
               run: ./scripts/build-package.sh
 

README.md

@@ -159,6 +159,13 @@ cmake --workflow --preset benchmark-workflow
 The benchmark target is separate from CTest because execution time varies
 between machines and system load.
 
+## Benchmark results
+
+The [benchmark dashboard](https://embtom.github.io/ctprintf/) tracks performance
+over time. Results are updated on pushes to `main` and weekly. To publish the
+dashboard, enable GitHub Pages for the repository with the `gh-pages` branch as
+the source.
+
 ## Creating a package
 
 CPack creates a gzip-compressed tarball containing the installable headers,