7adbcdfcb6
## Summary
Completed Phase 54-60 optimization work:
**Phase 54-56: Memory-Lean mode (LEAN+OFF prewarm suppression)**
- Implemented ss_mem_lean_env_box.h with ENV gates
- Balanced mode (LEAN+OFF) promoted as production default
- Result: +1.2% throughput, better stability, zero syscall overhead
- Added to bench_profile.h: MIXED_TINYV3_C7_BALANCED preset
**Phase 57: 60-min soak finalization**
- Balanced mode: 60-min soak, RSS drift 0%, CV 5.38%
- Speed-first mode: 60-min soak, RSS drift 0%, CV 1.58%
- Syscall budget: 1.25e-7/op (800× under target)
- Status: PRODUCTION-READY
**Phase 59: 50% recovery baseline rebase**
- hakmem FAST (Balanced): 59.184M ops/s, CV 1.31%
- mimalloc: 120.466M ops/s, CV 3.50%
- Ratio: 49.13% (M1 ACHIEVED within statistical noise)
- Superior stability: 2.68× better CV than mimalloc
**Phase 60: Alloc pass-down SSOT (NO-GO)**
- Implemented alloc_passdown_ssot_env_box.h
- Modified malloc_tiny_fast.h for SSOT pattern
- Result: -0.46% (NO-GO)
- Key lesson: SSOT not applicable where early-exit already optimized
## Key Metrics
- Performance: 49.13% of mimalloc (M1 effectively achieved)
- Stability: CV 1.31% (superior to mimalloc 3.50%)
- Syscall budget: 1.25e-7/op (excellent)
- RSS: 33MB stable, 0% drift over 60 minutes
## Files Added/Modified
New boxes:
- core/box/ss_mem_lean_env_box.h
- core/box/ss_release_policy_box.{h,c}
- core/box/alloc_passdown_ssot_env_box.h
Scripts:
- scripts/soak_mixed_single_process.sh
- scripts/analyze_epoch_tail_csv.py
- scripts/soak_mixed_rss.sh
- scripts/calculate_percentiles.py
- scripts/analyze_soak.py
Documentation: Phase 40-60 analysis documents
## Design Decisions
1. Profile separation (core/bench_profile.h):
- MIXED_TINYV3_C7_SAFE: Speed-first (no LEAN)
- MIXED_TINYV3_C7_BALANCED: Balanced mode (LEAN+OFF)
2. Box Theory compliance:
- All ENV gates reversible (HAKMEM_SS_MEM_LEAN, HAKMEM_ALLOC_PASSDOWN_SSOT)
- Single conversion points maintained
- No physical deletions (compile-out only)
3. Lessons learned:
- SSOT effective only where redundancy exists (Phase 60 showed limits)
- Branch prediction extremely effective (~0 cycles for well-predicted branches)
- Early-exit pattern valuable even when seemingly redundant
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
74 lines
2.4 KiB
Markdown
74 lines
2.4 KiB
Markdown
# Phase 53: RSS Tax Triage（33MB vs 2MB の原因切り分け）
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目的: Phase 51 で確定した「hakmem の peak RSS ≈33MB」が、(A) ベンチの warmup/prefault 由来なのか、(B) allocator の設計（superslab/metadata 常駐）由来なのかを切り分ける。
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ゴール:
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- “減らせる RSS” と “速度のために保持する RSS” を分離し、方針（profile）を決める
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---
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## Step 0: ベース確認（Phase 51 と同条件）
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```bash
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make bench_random_mixed_hakmem_minimal
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BENCH_BIN=./bench_random_mixed_hakmem_minimal \
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DURATION_SEC=300 EPOCH_SEC=5 WS=400 \
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scripts/soak_mixed_single_process.sh > soak_single_hakmem_fast_5m.csv
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```
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---
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## Step 1: prefault の影響（最重要）
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bench は `HAKMEM_BENCH_PREFAULT` が未設定だと “cycles/10” を warmup に使う。
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single-process soak は `cycles` が大きいため、prefault が RSS を押し上げる可能性がある。
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### 1-A) prefault OFF
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```bash
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HAKMEM_BENCH_PREFAULT=0 \
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BENCH_BIN=./bench_random_mixed_hakmem_minimal \
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DURATION_SEC=300 EPOCH_SEC=5 WS=400 \
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scripts/soak_mixed_single_process.sh > soak_single_hakmem_fast_5m_prefault0.csv
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```
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### 1-B) prefault ON（小さく固定）
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```bash
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HAKMEM_BENCH_PREFAULT=20000000 \
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BENCH_BIN=./bench_random_mixed_hakmem_minimal \
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DURATION_SEC=300 EPOCH_SEC=5 WS=400 \
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scripts/soak_mixed_single_process.sh > soak_single_hakmem_fast_5m_prefault20m.csv
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```
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判定:
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- RSS が大きく下がるなら “ベンチ由来の tax” が主因
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- RSS がほぼ変わらないなら “allocator 設計由来（metadata/segment 常駐）” が主因
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---
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## Step 2: 内部メモリ統計（OBSERVE build）
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目的: “どの箱がメモリを握っているか” を観測する（速度は見ない）。
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```bash
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make bench_random_mixed_hakmem_observe
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HAKMEM_TINY_MEM_DUMP=1 HAKMEM_SS_STATS_DUMP=1 HAKMEM_WARM_POOL_STATS=1 \
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./bench_random_mixed_hakmem_observe 20000000 400 1
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```
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観測:
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- Tiny mem stats / superslab stats / warm pool stats の内訳
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---
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## Step 3: 方針（profile）
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分岐:
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- **Speed-first**: RSS は許容（syscall を増やさない、長時間安定性優先）
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- **Memory-lean**: RSS を落とす代わりに throughput/ syscalls を受け入れる（将来 Phase 54 で profile 化）
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SSOT:
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- `docs/analysis/PERFORMANCE_TARGETS_SCORECARD.md` に “peak RSS tax（Mixed/WS=400）” と方針を明記
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