ci: Add a new benchmark recording workflow.

.github/workflows/benchmark.yml

@@ -0,0 +1,41 @@
+name: benchmark
+on:
+  pull_request: # for testing
+  push:
+    branches:
+      - main
+
+jobs:
+  benchmark:
+    runs-on: ubuntu-latest
+    permissions:
+      # For benchmark-action summary-always
+      issues: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v4
+        with:
+          go-version-file: 'go.mod'
+          cache: true
+      - name: benchmark
+        env:
+          HEAD_REF: ${{ env.GITHUB_REF_NAME }}
+        run: |
+          BENCH_COUNT=1 make bench
+      - uses: actions/cache@v4
+        with:
+          path: ./cache
+          key: ${{ runner.os }}-benchmark
+      - uses: benchmark-action/github-action-benchmark@v1
+        with:
+          # What benchmark tool the output.txt came from
+          tool: 'go'
+          # Where the output from the benchmark tool is stored
+          output-file-path: test-results/benchmark-results-${{ env.GITHUB_REF_NAME }}.txt
+          # Where the previous data file is stored
+          external-data-json-path: ./cache/benchmark-data.json
+          # Workflow will fail when an alert happens
+          fail-on-alert: true
+          comment-on-alert: true
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          summary-always: true

Makefile

@@ -200,7 +200,7 @@ $(TESTRESULTS)/test-output.xml $(TESTCOVERPROFILE): $(GOFILES) $(GOGENFILES) $(G
 bench: $(TESTRESULTS)/benchmark-results-$(HEAD_REF).txt
 $(TESTRESULTS)/benchmark-results-$(HEAD_REF).txt: $(GOFILES) $(GOGENFILES) $(GOTESTFILES) | print-version .dep-stamp
 	mkdir -p $(TESTRESULTS)
-	go test -cpu 1,2,4 -bench=. -count=$(BENCH_COUNT) -timeout=${benchtimeout} -run=^a ./... | tee $@
+	go test -cpu 1 -bench=BenchmarkMetric -count=$(BENCH_COUNT) -timeout=${benchtimeout} -run=^a ./... | tee $@
 
 .PHONY: benchstat
 benchstat: $(TESTRESULTS)/benchstat.txt