From 34730930e72781ad72d1505d8aaac1ed96cab8b8 Mon Sep 17 00:00:00 2001
From: Claude <claude@anthropic.com>
Date: Thu, 23 Jul 2026 15:00:29 +0000
Subject: [PATCH] feat(bench): E1 scheduler-count sweep orchestrator

Discriminates herd-contention vs stranding for the ka low-c latency
floor: sweeps URUS_SCHED_THREADS {1,2,4,8} x CONNS {4,8} over the plain
matrix (PLAIN_ONLY; close rides along as control). Per-cell audit
asserts the knob reached the server via plain_serve's stderr line.
Summary parser (req/s + p50/75/90/99, unit-normalized) validated
against the 96b40ad5 sweep output.
---
 scripts/e1-sched-sweep.sh | 89 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)
 create mode 100755 scripts/e1-sched-sweep.sh

diff --git a/scripts/e1-sched-sweep.sh b/scripts/e1-sched-sweep.sh
new file mode 100755
index 0000000..33d1f0a
--- /dev/null
+++ b/scripts/e1-sched-sweep.sh
@@ -0,0 +1,89 @@
+#!/usr/bin/env bash
+# E1: does the ka low-concurrency latency floor track idle-scheduler count?
+#
+# Mechanism under test (smarm): one shared level-triggered wake pipe; every
+# completion byte wakes ALL idle schedulers; one drain-lock winner; losers
+# stampede the timers/io/queue mutexes and re-sleep; `enqueue` is silent.
+# Prediction if right: at c <= 8, ka latency tail shrinks and throughput
+# rises as scheduler count drops (fewer idle pollers -> smaller herd);
+# close mode (control) stays flat or worsens as threads drop.
+#
+# Sweeps URUS_SCHED_THREADS x CONNS over the plain ka/close matrix,
+# PLAIN_ONLY — causal cells are irrelevant to E1. wrk side is byte-identical
+# to the 96b40ad5 conns sweep (THREADS=4, --latency) for comparability.
+#
+# Knobs: THREADS_SET CONNS_SET DUR REPS OUT (+ everything the matrix takes)
+set -euo pipefail
+cd "$(dirname "$0")/.."
+
+THREADS_SET="${THREADS_SET:-1 2 4 8}"
+CONNS_SET="${CONNS_SET:-4 8}"
+DUR="${DUR:-15}"
+REPS="${REPS:-2}"
+OUT="${OUT:-/workspace/results}"
+
+mkdir -p "$OUT"
+say() { echo "[$(date +%H:%M:%S)] $*" | tee -a "$OUT/e1.log"; }
+
+for t in $THREADS_SET; do
+  for c in $CONNS_SET; do
+    cell="$OUT/t${t}-c${c}"
+    say "=== E1 cell: sched_threads=$t conns=$c -> $cell ==="
+    URUS_SCHED_THREADS="$t" PLAIN_ONLY=1 \
+      DUR="$DUR" REPS="$REPS" CONNS="$c" OUT="$cell" \
+      bash scripts/ka-close-matrix.sh
+    # Cell audit: the knob must have actually reached the server. A cell
+    # whose server silently ran at default threads poisons the sweep — the
+    # exact failure class per-cell verification exists to catch.
+    for m in ka close; do
+      if ! grep -q "scheduler_threads=Some($t)" "$cell/plain-$m/server.log"; then
+        say "FATAL: t=$t c=$c mode=$m server.log lacks scheduler_threads=Some($t)"
+        exit 1
+      fi
+    done
+    say "cell t=$t c=$c audit OK"
+  done
+done
+
+say "=== E1 SUMMARY ==="
+python3 - "$OUT" <<'PY' | tee -a "$OUT/e1.log"
+import re, sys, pathlib, statistics
+
+out = pathlib.Path(sys.argv[1])
+
+def ms(tok):
+    m = re.match(r"([\d.]+)(us|ms|s)$", tok)
+    if not m:
+        return None
+    v = float(m.group(1))
+    return {"us": v / 1000, "ms": v, "s": v * 1000}[m.group(2)]
+
+def cell_stats(d):
+    reps, pcts = [], {}
+    for rep in sorted(d.glob("rep*.txt")):
+        t = rep.read_text()
+        m = re.search(r"Requests/sec:\s+([\d.]+)", t)
+        if m:
+            reps.append(float(m.group(1)))
+        for p, tok in re.findall(r"^\s+(50|75|90|99)%\s+(\S+)$", t, re.M):
+            pcts.setdefault(p, []).append(ms(tok))
+    if not reps:
+        return None
+    return (statistics.mean(reps),
+            {p: statistics.mean([v for v in vs if v is not None])
+             for p, vs in pcts.items()})
+
+cells = sorted(out.glob("t*-c*"))
+hdr = f"{'cell':>10} {'mode':>6} {'req/s':>9} {'p50ms':>7} {'p75ms':>7} {'p90ms':>7} {'p99ms':>7}"
+print(hdr); print("-" * len(hdr))
+for cell in cells:
+    for mode in ("ka", "close"):
+        s = cell_stats(cell / f"plain-{mode}")
+        if s is None:
+            continue
+        rps, p = s
+        print(f"{cell.name:>10} {mode:>6} {rps:>9.0f} "
+              f"{p.get('50', float('nan')):>7.3f} {p.get('75', float('nan')):>7.3f} "
+              f"{p.get('90', float('nan')):>7.3f} {p.get('99', float('nan')):>7.3f}")
+PY
+say "=== E1 DONE ==="