Say what snapshots cost the owner, and what reusing their nodes gave (107)

Most of it was the allocator: leaves past glibc's thread cache, freed by
whichever thread let the last snapshot go. jemalloc was 11-14% faster
at more memory; reusing the nodes in Pure gave a median +9.4% over six
pairs, 4-8% less CPU a transaction in all six, and 1.97x the state bytes
resident where it was 2.18x. TPC-C in RAM is now 4.0x a tuned SQLite at
W=1 and 3.5x at W=4; finding items is the owner's largest part now.

1 files changed, 50 insertions, 0 deletions

diff --git a/research/experiments/023-node-reuse/summary.py b/research/experiments/023-node-reuse/summary.py
new file mode 100644
index 0000000..e5fbbb0
--- /dev/null
+++ b/research/experiments/023-node-reuse/summary.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+"""docs/research/107's numbers from the result files beside this one: the
+allocators, before and after in turns (six pairs: runs.sh made the first
+three, before first; three more followed, after first), and 106's RAM
+matrix again (with 022-tpcc-grouped/tables.py)."""
+import importlib.util
+import json
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+
+
+def pure_run(name):
+    run = end = None
+    for line in (HERE / f'2026-09-30-{name}-linux-aarch64.jsonl').read_text().splitlines():
+        r = json.loads(line)
+        run = r if r['step'] == 'run' else run
+        end = r if r['step'] == 'end' else end
+    return run, end
+
+
+def row(label, name):
+    run, end = pure_run(name)
+    ratio = end['pure_resident_mib'] / end['pure_state_mib']
+    print(f"| {label} | {run['transactions_per_second']:,} | {run['cpu_us_per_transaction']} | "
+          f"{run['core_shares']['pure-owner']:.2f} | {end['pure_resident_mib']:.0f} / {end['pure_state_mib']:.0f} MiB "
+          f"({ratio:.2f}) |")
+    return run['transactions_per_second']
+
+
+print('| | 초당 거래 | 거래당 CPU (µs) | 소유자의 코어 몫 | 상주 / 상태 (배수) |')
+print('|---|---:|---:|---:|---:|')
+for name, label in (('allocator-glibc-1', 'glibc'), ('allocator-jemalloc-1', 'jemalloc'),
+                    ('allocator-tcache-1', 'glibc, tcache_max=4096'), ('allocator-glibc-2', 'glibc'),
+                    ('allocator-jemalloc-2', 'jemalloc')):
+    row(label, name)
+print()
+print('| | 초당 거래 | 거래당 CPU (µs) | 소유자의 코어 몫 | 상주 / 상태 (배수) |')
+print('|---|---:|---:|---:|---:|')
+for round in range(1, 7):  # 1-3 before first, 4-6 after first
+    before = row(f'전, {round}', f'before-{round}')
+    after = row(f'후, {round}', f'after-{round}')
+    print(f'| ({(after / before - 1) * 100:+.1f}%) | | | | |')
+print()
+spec = importlib.util.spec_from_file_location('tables', HERE.parent / '022-tpcc-grouped' / 'tables.py')
+tables = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(tables)
+tables.OUT = HERE
+for name in ('ram-w1', 'ram-w4'):
+    tables.table(name, False)