Phase 4 E1: ENV Snapshot Consolidation - GO (+3.92% avg, +4.01% median)
Target: Consolidate 3 ENV gate TLS reads → 1 TLS read
- tiny_c7_ultra_enabled_env(): 1.28% self
- tiny_front_v3_enabled(): 1.01% self
- tiny_metadata_cache_enabled(): 0.97% self
- Total overhead: 3.26% self (perf profile analysis)
Implementation:
- core/box/hakmem_env_snapshot_box.h (new): ENV snapshot struct & API
- core/box/hakmem_env_snapshot_box.c (new): TLS snapshot implementation
- core/front/malloc_tiny_fast.h: Migrated 5 call sites to snapshot
- core/box/tiny_legacy_fallback_box.h: Migrated 2 call sites
- core/box/tiny_metadata_cache_hot_box.h: Migrated 1 call site
- core/bench_profile.h: Added hakmem_env_snapshot_refresh_from_env()
- Makefile: Added hakmem_env_snapshot_box.o to build
- ENV gate: HAKMEM_ENV_SNAPSHOT=0/1 (default: 0, research box)
A/B Test Results (Mixed, 10-run, 20M iters):
- Baseline (E1=0): 43,617,549 ops/s (avg), 43,562,895 ops/s (median)
- Optimized (E1=1): 45,327,239 ops/s (avg), 45,309,218 ops/s (median)
- Improvement: avg +3.92%, median +4.01%
Decision: GO (+3.92% >= +2.5% threshold)
- Action: Keep as research box (default OFF) for Phase 4
- Next: Consider promotion to default in MIXED_TINYV3_C7_SAFE preset
Design Rationale:
- Shape optimizations (B3, D3) reached saturation (+0.56% NEUTRAL)
- Shift to memory/TLS overhead optimization (new optimization frontier)
- Pattern: Similar to existing tiny_front_v3_snapshot (proven approach)
- Expected: +1-3% from 3.26% ENV overhead → Achieved: +3.92%
Technical Details:
- Consolidation: 3 TLS reads → 1 TLS read (66% reduction)
- Learner interlock: tiny_metadata_cache_eff pre-computed in snapshot
- Version sync: Refreshes on small_policy_v7_version_changed()
- Fallback safety: Existing ENV gates still available when E1=0
🤖 Generated with Claude Code
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
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