4a070d8a14
Target: Consolidate free wrapper TLS reads (2→1)
- free() is 25.26% self% (top hot spot)
- Strategy: Apply E1 success pattern (ENV snapshot) to free path
Implementation:
- ENV gate: HAKMEM_FREE_WRAPPER_ENV_SNAPSHOT=0/1 (default 0)
- core/box/free_wrapper_env_snapshot_box.{h,c}: New box
- Consolidates 2 TLS reads → 1 TLS read (50% reduction)
- Reduces 4 branches → 3 branches (25% reduction)
- Lazy init with probe window (bench_profile putenv sync)
- core/box/hak_wrappers.inc.h: Integration in free() wrapper
- Makefile: Add free_wrapper_env_snapshot_box.o to all targets
A/B Test Results (Mixed, 10-run, 20M iters):
- Baseline (SNAPSHOT=0): 45.35M ops/s (mean), 45.31M ops/s (median)
- Optimized (SNAPSHOT=1): 46.94M ops/s (mean), 47.15M ops/s (median)
- Improvement: +3.51% mean, +4.07% median
Decision: GO (+3.51% >= +1.0% threshold)
- Exceeded conservative estimate (+1.5% → +3.51%)
- Similar efficiency to E1 (+3.92%)
- Health check: PASS (all profiles)
- Action: PROMOTED to MIXED_TINYV3_C7_SAFE preset
Phase 5 Cumulative:
- E1 (ENV Snapshot): +3.92%
- E4-1 (Free Wrapper Snapshot): +3.51%
- Total Phase 4-5: ~+7.5%
E3-4 Correction:
- Phase 4 E3-4 (ENV Constructor Init): NO-GO / FROZEN
- Initial A/B showed +4.75%, but investigation revealed:
- Branch prediction hint mismatch (UNLIKELY with always-true)
- Retest confirmed -1.78% regression
- Root cause: __builtin_expect(..., 0) with ctor_mode==1
- Decision: Freeze as research box (default OFF)
- Learning: Branch hints need careful tuning, TLS consolidation safer
Deliverables:
- docs/analysis/PHASE5_E4_FREE_GATE_OPTIMIZATION_1_DESIGN.md
- docs/analysis/PHASE5_E4_1_FREE_WRAPPER_ENV_SNAPSHOT_NEXT_INSTRUCTIONS.md
- docs/analysis/PHASE5_E4_2_MALLOC_WRAPPER_ENV_SNAPSHOT_NEXT_INSTRUCTIONS.md (next)
- docs/analysis/PHASE5_POST_E1_NEXT_INSTRUCTIONS.md
- docs/analysis/ENV_PROFILE_PRESETS.md (E4-1 added, E3-4 corrected)
- CURRENT_TASK.md (E4-1 complete, E3-4 frozen)
- core/bench_profile.h (E4-1 promoted to default)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
72 lines
1.8 KiB
Markdown
72 lines
1.8 KiB
Markdown
# Phase 5: Post-E1 Baseline & Next Target（次の指示書）
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## Status（2025-12-14）
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- Phase 4 の勝ち箱は **E1（ENV Snapshot）**（`MIXED_TINYV3_C7_SAFE` で default 化）
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- E3-4（ENV CTOR）は **NO-GO / freeze**
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- Phase 5 の勝ち箱: **E4-1（free wrapper snapshot）**（`MIXED_TINYV3_C7_SAFE` で default 化）
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- 次は “形” ではなく **wrapper 入口の ENV/TLS** を削る（E4-2）か、perf で self% ≥ 5% を殴る
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---
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## Step 0: Baseline 固定（Mixed）
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```sh
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HAKMEM_PROFILE=MIXED_TINYV3_C7_SAFE ./bench_random_mixed_hakmem 20000000 400 1
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```
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注意:
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- 以後の A/B はこのプロファイル（=E1 ON）を基準にする
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---
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## Step 1: perf で “芯” を選ぶ（self% ≥ 5%）
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```sh
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HAKMEM_PROFILE=MIXED_TINYV3_C7_SAFE perf record -F 99 -- \
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./bench_random_mixed_hakmem 20000000 400 1
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perf report --stdio --no-children
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```
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GO/NO-GO:
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- self% が **5% 未満**の最適化は原則 NO-GO（まず他を削る）
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---
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## Step 2: 研究箱の候補を 1 つに絞る（Box Theory）
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要件:
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- L0 ENV gate（default OFF）を必ず用意（戻せる）
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- 境界は 1 箇所（変換点を増やさない）
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- 可視化はカウンタ 1 本まで（常時ログ禁止）
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---
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## Step 3: A/B で GO 判定（Mixed）
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Mixed 10-run:
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- GO: mean **+1.0% 以上**
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- ±1%: NEUTRAL（freeze）
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- -1% 以下: NO-GO（freeze）
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---
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## Step 4: 健康診断
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```sh
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scripts/verify_health_profiles.sh
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```
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---
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## Step 5: 昇格
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- 勝ち箱だけを `core/bench_profile.h` のプリセットへ
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- `docs/analysis/ENV_PROFILE_PRESETS.md` に結果＋rollback を追記
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- `CURRENT_TASK.md` を更新
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## Next
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- E4-1 昇格: `docs/analysis/PHASE5_E4_1_FREE_WRAPPER_ENV_SNAPSHOT_NEXT_INSTRUCTIONS.md`
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- E4-2 設計/実装: `docs/analysis/PHASE5_E4_2_MALLOC_WRAPPER_ENV_SNAPSHOT_NEXT_INSTRUCTIONS.md`
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