Simplify speedy benchmark

This PR drops two things:

1. The check that the benchmark hasn’t been modified. This hasn’t ever
been useful and it keeps being annoying.
2. It stops the comparison against the old version and instead just
benchmarks the current version. We really only care about the day to
day changes. Comparing against an arbitrary year old version has lost
all meaning at this point.

changelog_begin
changelog_end

azure-pipelines.yml

@@ -19,30 +19,6 @@ pr: none
 jobs:
 - template: ci/build.yml
 
-- job: check_perf_test
-  pool:
-    name: ubuntu_20_04
-    demands: assignment -equals default
-  steps:
-  - bash: |
-      TEST_SHA=$(cat ci/cron/perf/test_sha)
-      LAST_CHANGES=$(git log -n1 --format=%H daml-lf/scenario-interpreter/src/perf)
-      CURRENT_SHA=$(git rev-parse HEAD)
-      if [ "$TEST_SHA" != "$LAST_CHANGES" ]; then
-          if [ "$LAST_CHANGES" = "$CURRENT_SHA" ]; then
-              curl -XPOST \
-                   -i \
-                   -H 'Content-Type: application/json' \
-                   --data "{\"text\":\"<!here> Perf tests seem to have changed. Please manually check:\n\`\`\`\ngit diff $TEST_SHA $LAST_CHANGES -- daml-lf/scenario-interpreter/src/perf\n\`\`\`\nand update accordingly. If the change is benign, update \`ci/cron/perf/test_sha\` to \`$LAST_CHANGES\`. With no intervention, you will no longer get performance reports.\"}" \
-                   $(Slack.ci-failures-daml)
-          else
-              echo "Changes detected, but not from this commit."
-          fi
-      else
-          echo "No change detected."
-      fi
-    displayName: check perf changes
-
 - job: release
   dependsOn: [ "check_for_release", "Linux", "macOS", "Windows" ]
   condition: and(succeeded(),

ci/cron/daily-compat.yml

@@ -90,25 +90,17 @@ jobs:
           eval "$(dev-env/bin/dade assist)"
           source $(bash_lib)
 
-          BASELINE="cebc26af88efef4a7c81c62b0c14353f829b755e"
-          TEST_SHA=$(cat ci/cron/perf/test_sha)
           OUT="$(Build.StagingDirectory)/perf-results.json"
 
           START=$(date -u +%Y%m%d_%H%M%SZ)
 
-          if git diff --exit-code $TEST_SHA -- daml-lf/scenario-interpreter/src/perf >&2; then
-              # no changes, all good
-              ci/cron/perf/compare.sh $BASELINE > "$OUT"
-              cat "$OUT"
-          else
-              # the tests have changed, we need to figure out what to do with
-              # the baseline.
-              echo "Baseline no longer valid, needs manual correction." > "$OUT"
-          fi
+          ci/cron/perf/bench.sh > "$OUT"
+
+          cat $OUT
 
           gcs "$GCRED" cp "$OUT" gs://daml-data/perf/speedy/$START.json
 
-          setvar speedup "$(jq -r '.speedup' "$OUT")"
+          setvar speedy_perf "$(jq -r '.current-perf' "$OUT")"
 
         displayName: measure perf
         name: out
@@ -329,7 +321,7 @@ jobs:
       compatibility: $[ dependencies.compatibility.result ]
       compatibility_windows: $[ dependencies.compatibility_windows.result ]
       perf_speedy: $[ dependencies.perf_speedy.result ]
-      speedup: $[ dependencies.perf_speedy.outputs['out.speedup'] ]
+      speedy_perf: $[ dependencies.perf_speedy.outputs['out.speedy_perf'] ]
       perf_http_json: $[ dependencies.perf_http_json.result ]
       check_releases: $[ dependencies.check_releases.result ]
       blackduck_scan: $[ dependencies.blackduck_scan.result ]
@@ -355,7 +347,7 @@ jobs:
            && "$(check_releases)" == "Succeeded"
            && ("$(blackduck_scan)" == "Succeeded" || "$(blackduck_scan)" == "Skipped")
            && ("$(run_notices_pr_build)" == "Succeeded" || "$(run_notices_pr_build)" == "Skipped") ]]; then
-            tell_slack "Daily tests passed: $COMMIT_LINK (speedup: $(speedup))." "$(Slack.ci-failures-daml)"
+            tell_slack "Daily tests passed: $COMMIT_LINK (speedy_perf: $(speedy_perf))." "$(Slack.ci-failures-daml)"
         else
             tell_slack "Daily tests failed: $COMMIT_LINK." "$(Slack.ci-failures-daml)"
         fi

ci/cron/perf/bench.sh

@@ -0,0 +1,23 @@
+# Copyright (c) 2021 Digital Asset (Switzerland) GmbH and/or its affiliates. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+#!/usr/bin/env bash
+
+set -euox pipefail
+
+measure() {
+    local out=$(mktemp -d)/out.json
+    bazel run daml-lf/scenario-interpreter:scenario-perf -- -rf json -rff $out >&2
+    cat $out | jq '.[0].primaryMetric.score'
+}
+
+main() {
+  local current=$(git rev-parse HEAD)
+
+  local current_perf=$(measure)
+  if [ "" = "$current_perf" ]; then exit 1; fi
+
+  echo '{"current-perf": '$current_perf', "current-sha": "'$current'"}'
+}
+
+main