47 lines
1.6 KiB
Markdown
47 lines
1.6 KiB
Markdown
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# Phase 3 D1: Free Path Route Cache 設計メモ
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## 目的
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Free path の `tiny_route_for_class()` コストを削減（4.39% self + 24.78% children）
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## 観察
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- free() → tiny_free_fast() → tiny_route_for_class() → g_tiny_route_snapshot_done check
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- Route determination が free path の支配的なボトルネック
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- Phase 3 C3 (Static routing for alloc) と同じアプローチを free に適用
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## 実装アプローチ
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### L0: Env（戻せる）
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- `HAKMEM_FREE_STATIC_ROUTE=0/1` (default: 0, OFF)
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### L1: IntegrationBox（境界: 1箇所）
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`tiny_route_env_box.h` に既存する `g_tiny_route` を free path で活用：
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- `tiny_route_for_class()` を呼ばずに直接 route を決定
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- Cache invalidate: policy version change on sync
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### 実装指示
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**File 1**: `core/box/tiny_free_route_cache_env_box.h` (新規)
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- Inline function: `tiny_free_static_route_enabled()`
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- Check `HAKMEM_FREE_STATIC_ROUTE` ENV
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- Lazy init with -1 sentinel
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- Return cached value
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**File 2**: Modify `core/box/tiny_route_env_box.h` (既存)
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- Add: `SmallRouteKind tiny_route_get_kind(int class_idx)` if not exist
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- Use existing `g_tiny_route.route_kind[class]` cache
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**File 3**: Modify `core/front/tiny_legacy_fallback_box.h` (既存)
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- In `tiny_legacy_fallback_free_base()` function
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- Check: `if (tiny_free_static_route_enabled())` before calling `tiny_route_for_class()`
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- Fallback: call `tiny_route_for_class()` if disabled
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## A/B テスト
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- Mixed (10-run): HAKMEM_FREE_STATIC_ROUTE=0 vs =1
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- GO: +1.0%+, NO-GO: -1.0%-
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## 期待
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- tiny_route_for_class() call 削減 → L1 cache pressure 低下
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- +1-2% gain in free path
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