cbb35ee27f
Phase 13 v1: Header Write Elimination (C7 preserve header)
- Verdict: NEUTRAL (+0.78%)
- Implementation: HAKMEM_TINY_C7_PRESERVE_HEADER ENV gate (default OFF)
- Makes C7 nextptr offset conditional (0→1 when enabled)
- 4-point matrix A/B test results:
* Case A (baseline): 51.49M ops/s
* Case B (WRITE_ONCE=1): 52.07M ops/s (+1.13%)
* Case C (C7_PRESERVE=1): 51.36M ops/s (-0.26%)
* Case D (both): 51.89M ops/s (+0.78% NEUTRAL)
- Action: Freeze as research box (default OFF, manual opt-in)
Phase 5 E5-2: Header Write-Once retest (promotion test)
- Verdict: NEUTRAL (+0.54%)
- Motivation: Phase 13 Case B showed +1.13%, re-tested with dedicated 20-run
- Results (20-run):
* Case A (baseline): 51.10M ops/s
* Case B (WRITE_ONCE=1): 51.37M ops/s (+0.54%)
- Previous test: +0.45% (consistent with NEUTRAL)
- Action: Keep as research box (default OFF, manual opt-in)
Key findings:
- Header write tax optimization shows consistent NEUTRAL results
- Neither Phase 13 v1 nor E5-2 reaches GO threshold (+1.0%)
- Both implemented as reversible ENV gates for future research
Files changed:
- New: core/box/tiny_c7_preserve_header_env_box.{c,h}
- Modified: core/box/tiny_layout_box.h (C7 offset conditional)
- Modified: core/tiny_nextptr.h, core/box/tiny_header_box.h (comments)
- Modified: core/bench_profile.h (refresh sync)
- Modified: Makefile (add new .o files)
- Modified: scripts/run_mixed_10_cleanenv.sh (add C7_PRESERVE ENV)
- Docs: PHASE13_*, PHASE5_E5_2_HEADER_WRITE_ONCE_* (design/results)
Next: Phase 14 (Pointer-chase reduction, tcache-style intrusive LIFO)
🤖 Generated with Claude Code
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Docs Overview
このフォルダは hakmem の設計・計測・運用メモを体系化して管理する場所です。
- INDEX.md: 目次（各ドキュメントへのリンク）
- benchmarks/: ベンチマーク手順とスイープ結果の保存先
- specs/: 現在の仕様（SACS‑3/HW/ENV）を集約
- roadmap/: これからの実装計画・優先度・タスク
運用ルール（提案）
- 1つの変更/計測のまとまりにつき1ファイル（or 1フォルダ）
- 再現コマンド・環境変数・ハード構成は必ず記載
- 大きな連続出力はファイルへ保存し、本文からは抜粋/要約を記載