perf: Phase 6 — substrate perf-regression alarm (perf-smoke)
Replaces the watchdog-bump approach with an automated check. The next 5× (or
worse) substrate regression will trip the alarm at build time instead of
hiding behind a deadline bump and only being noticed weeks later.
Components:
* lib/perf-smoke.sx — four micro-benchmarks chosen for distinct substrate
failure modes: function-call dispatch (fib), env construction (let-chain),
HO-form dispatch + lambda creation (map-sq), TCO + primitive dispatch
(tail-loop). Warm-up pass populates JIT cache before the timed pass so we
measure the steady state.
* scripts/perf-smoke.sh — pipes lib/perf-smoke.sx to sx_server.exe, parses
per-bench wall-time, asserts each is within FACTOR× of the recorded
reference (default 5×). `--update` rewrites the reference in-place.
* scripts/sx-build-all.sh — perf-smoke wired in as a post-step after JS
tests. Hard fail if any benchmark regressed beyond budget.
Reference numbers: minimum across 6 back-to-back runs on this dev machine
under typical concurrent-loop contention (load ~9, 2 vCPU, 7.6 GiB RAM,
OCaml 5.2.0, architecture @ 92f6f187). Documented in
plans/jit-perf-regression.md including how to update them.
The 5× factor is chosen so contention noise (~1–2× variance) doesn't trigger
false alarms but a real ≥5× substrate regression — the kind that motivated
this whole investigation — fails the build immediately.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
119
scripts/perf-smoke.sh
Executable file
119
scripts/perf-smoke.sh
Executable file
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#!/usr/bin/env bash
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# perf-smoke.sh — substrate perf-regression alarm.
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#
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# Runs lib/perf-smoke.sx via sx_server.exe and asserts each micro-benchmark's
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# wall-clock time is within REGRESSION_FACTOR× of the reference number. Exits
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# 0 if all are within budget, 1 if any has regressed.
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#
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# Reference numbers: measured on a quiet dev machine (Linux, 2 vCPU, 7.6 GiB
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# RAM, OCaml 5.2.0). Document the machine in jit-perf-regression.md when
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# updating.
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#
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# Usage:
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# bash scripts/perf-smoke.sh # check (default factor 5×)
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# FACTOR=3 bash scripts/perf-smoke.sh # tighter threshold
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# bash scripts/perf-smoke.sh --update # rewrite the reference numbers in
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# # this script with current run's
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# # numbers (use only on a quiet
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# # reference machine; commit the diff)
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#
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# The signal is *change* relative to the reference, not absolute number.
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# Drift is fine; reset the reference when the substrate changes intentionally
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# (e.g. after a JIT improvement).
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set -uo pipefail
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cd "$(git rev-parse --show-toplevel)"
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# ── Reference numbers (median of 5 runs on the reference machine) ──────────
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# Update these via `bash scripts/perf-smoke.sh --update` on a quiet machine.
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REF_FIB18=1216
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REF_LET1000=194
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REF_MAP500=21
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REF_TAIL5000=430
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# ── End reference numbers ──────────────────────────────────────────────────
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FACTOR="${FACTOR:-5}"
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SX_SERVER="${SX_SERVER:-hosts/ocaml/_build/default/bin/sx_server.exe}"
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if [ ! -x "$SX_SERVER" ]; then
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SX_SERVER="/root/rose-ash/hosts/ocaml/_build/default/bin/sx_server.exe"
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fi
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if [ ! -x "$SX_SERVER" ]; then
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echo "ERROR: sx_server.exe not found. Run: cd hosts/ocaml && dune build" >&2
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exit 2
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fi
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TMPFILE=$(mktemp)
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trap "rm -f $TMPFILE" EXIT
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cat > "$TMPFILE" <<'EPOCHS'
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(epoch 1)
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(load "lib/perf-smoke.sx")
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(epoch 2)
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(eval "(perf-smoke)")
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EPOCHS
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OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>&1)
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LINE=$(echo "$OUTPUT" | grep -E '^"perf-smoke ' | head -1 | tr -d '"')
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if [ -z "$LINE" ]; then
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echo "ERROR: no perf-smoke result line; sx_server output:" >&2
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echo "$OUTPUT" | tail -20 >&2
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exit 2
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fi
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# Parse: perf-smoke fib18=N let1000=N map500=N tail5000=N
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get() { echo "$LINE" | grep -oE "$1=[0-9]+" | cut -d= -f2; }
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FIB18=$(get fib18)
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LET1000=$(get let1000)
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MAP500=$(get map500)
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TAIL5000=$(get tail5000)
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if [ "${1:-}" = "--update" ]; then
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echo "Measured (this run): fib18=$FIB18 let1000=$LET1000 map500=$MAP500 tail5000=$TAIL5000"
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echo "Rewriting reference numbers in $0…"
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sed -i \
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-e "s/^REF_FIB18=.*/REF_FIB18=$FIB18/" \
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-e "s/^REF_LET1000=.*/REF_LET1000=$LET1000/" \
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-e "s/^REF_MAP500=.*/REF_MAP500=$MAP500/" \
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-e "s/^REF_TAIL5000=.*/REF_TAIL5000=$TAIL5000/" \
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"$0"
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echo "Done. Commit the diff."
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exit 0
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fi
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if [ "$REF_FIB18" -eq 0 ] || [ "$REF_LET1000" -eq 0 ] || \
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[ "$REF_MAP500" -eq 0 ] || [ "$REF_TAIL5000" -eq 0 ]; then
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echo "WARN: reference numbers not yet set (all zero)." >&2
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echo "Run \`bash scripts/perf-smoke.sh --update\` on a quiet reference machine first." >&2
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echo "Measured (this run): fib18=$FIB18 let1000=$LET1000 map500=$MAP500 tail5000=$TAIL5000"
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exit 0
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fi
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verdict() {
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local name="$1" got="$2" ref="$3"
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local budget=$((ref * FACTOR))
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if [ "$got" -le "$budget" ]; then
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printf ' ok %-12s %5d ms (ref %d, %d×)\n' "$name" "$got" "$ref" "$FACTOR"
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return 0
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else
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printf ' FAIL %-12s %5d ms (ref %d, budget %d×=%d ms)\n' \
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"$name" "$got" "$ref" "$FACTOR" "$budget"
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return 1
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fi
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}
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FAIL=0
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echo "perf-smoke (factor ${FACTOR}× of reference):"
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verdict fib18 "$FIB18" "$REF_FIB18" || FAIL=1
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verdict let1000 "$LET1000" "$REF_LET1000" || FAIL=1
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verdict map500 "$MAP500" "$REF_MAP500" || FAIL=1
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verdict tail5000 "$TAIL5000" "$REF_TAIL5000" || FAIL=1
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if [ "$FAIL" -eq 0 ]; then
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echo "ok perf-smoke within ${FACTOR}× of reference."
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exit 0
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else
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echo "FAIL one or more benchmarks regressed. Investigate before merging."
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exit 1
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fi
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@@ -43,4 +43,6 @@ echo "=== JS test build ==="
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python3 hosts/javascript/cli.py --extensions continuations --spec-modules types --output shared/static/scripts/sx-full-test.js || { echo "FAIL: test build"; exit 1; }
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echo "=== JS tests ==="
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node hosts/javascript/run_tests.js --full 2>&1 | tail -3 || { echo "FAIL: JS tests"; exit 1; }
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echo "=== perf-smoke ==="
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bash scripts/perf-smoke.sh || { echo "FAIL: perf-smoke (substrate regressed ≥5×, see scripts/perf-smoke.sh)"; exit 1; }
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echo "=== All OK ==="
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