Commit Graph

1 Commits

Author SHA1 Message Date
deecda7336 Phase 3 C2: Slab Metadata Cache Optimization (3 patches) - NEUTRAL
Patch 1: Policy Hot Cache
- Add TinyPolicyHot struct (route_kind[8] cached in TLS)
- Eliminate policy_snapshot() calls (~2 memory ops saved)
- Safety: disabled when learner v7 active
- Files: tiny_metadata_cache_env_box.h, tiny_metadata_cache_hot_box.{h,c}
- Integration: malloc_tiny_fast.h route selection

Patch 2: First Page Inline Cache
- Cache current slab page pointer in TLS per-class
- Avoid superslab metadata lookup (1-2 memory ops)
- Fast-path in tiny_legacy_fallback_free_base()
- Files: tiny_first_page_cache.h, tiny_unified_cache.c
- Integration: tiny_legacy_fallback_box.h

Patch 3: Bounds Check Compile-out
- Hardcode unified_cache capacity as MACRO constant
- Eliminate modulo operation (constant fold)
- Macros: TINY_UNIFIED_CACHE_CAPACITY_POW2=11, CAPACITY=2048, MASK=2047
- File: tiny_unified_cache.h

A/B Test Results (Mixed, 10-run):
- Baseline (C2=0): 40.43M ops/s (avg), 40.72M ops/s (median)
- Optimized (C2=1): 40.25M ops/s (avg), 40.29M ops/s (median)
- Improvement: -0.45% (avg), -1.06% (median)
- DECISION: NEUTRAL (within ±1.0% threshold)
- Action: Keep as research box (ENV gate OFF by default)

Cumulative Gain (Phase 2-3):
- B3 (Routing shape): +2.89%
- B4 (Wrapper split): +1.47%
- C3 (Static routing): +2.20%
- C2 (Metadata cache): -0.45%
- Total: ~6.1% (from baseline 37.5M → 39.8M ops/s)

🤖 Generated with Claude Code

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-13 19:19:42 +09:00