Phase 15 v1: UnifiedCache FIFO→LIFO NEUTRAL (-0.70% Mixed, +0.42% C7)

Transform existing array-based UnifiedCache from FIFO ring to LIFO stack.

A/B Results:
- Mixed (16-1024B): -0.70% (52,965,966 → 52,593,948 ops/s)
- C7-only (1025-2048B): +0.42% (78,010,783 → 78,335,509 ops/s)

Verdict: NEUTRAL (both below +1.0% GO threshold) - freeze as research box

Implementation:
- L0 ENV gate: tiny_unified_lifo_env_box.{h,c} (HAKMEM_TINY_UNIFIED_LIFO=0/1)
- L1 LIFO ops: tiny_unified_lifo_box.h (unified_cache_try_pop/push_lifo)
- L2 integration: tiny_front_hot_box.h (mode check at entry)
- Reuses existing slots[] array (no intrusive pointers)

Root Causes:
1. Mode check overhead (tiny_unified_lifo_enabled() call)
2. Minimal LIFO vs FIFO locality delta in practice
3. Existing FIFO ring already well-optimized

Bonus Fix: LTO bug for tiny_c7_preserve_header_enabled() (Phase 13/14 latent issue)
- Converted static inline to extern + non-inline implementation
- Fixes undefined reference during LTO linking

Design: docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_DESIGN.md
Results: docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_AB_TEST_RESULTS.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
This commit is contained in:
Moe Charm (CI)
2025-12-15 02:19:26 +09:00
parent b7e01a9419
commit 87fa27518c
14 changed files with 712 additions and 17 deletions

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@ -268,6 +268,80 @@ Phase 6-10 で達成した累積改善:
**Future Work**: Consider per-class cap tuning or alternative pointer-chase reduction strategies
### Phase 14 v2: Pointer Chase Reduction — Hot Path Integration — NEUTRAL (+0.08%) ⚠️ RESEARCH BOX
**Date**: 2025-12-15
**Verdict**: **NEUTRAL (+0.08% Mixed)** / **-0.39% (C7-only)** — research box 維持default OFF
**Motivation**: Phase 14 v1 は “alloc 側が tcache を消費していない” 疑義があったため、`tiny_front_hot_box` の hot alloc/free に tcache を接続して再 A/B を実施。
**Results**:
| Workload | TCACHE=0 | TCACHE=1 | Delta |
|---------|----------|----------|-------|
| Mixed (161024B) | 51,287,515 | 51,330,213 | **+0.08%** |
| C7-only | 80,975,651 | 80,660,283 | **-0.39%** |
**Conclusion**:
- v2 で通電は確認したが、Mixed の “本線” 改善にはならずGO 閾値 +1.0% 未達)
- Phase 14tcache-style intrusive LIFOは現状 **freeze 維持**が妥当
**Possible root causes**(次に掘るなら):
1. `tiny_next_load/store` の fence/補助処理が TLS-only tcache には重すぎる可能性
2. `tiny_tcache_enabled/cap` の固定費load/branchが savings を相殺
3. Mixed では bin ごとの hit 率が薄いworkload mismatch
**Refs**:
- v2 results: `docs/analysis/PHASE14_POINTER_CHASE_REDUCTION_2_AB_TEST_RESULTS.md`
- v2 instructions: `docs/analysis/PHASE14_POINTER_CHASE_REDUCTION_2_NEXT_INSTRUCTIONS.md`
---
### Phase 15 v1: UnifiedCache FIFO→LIFO (Stack) — NEUTRAL (-0.70% Mixed, +0.42% C7) ⚠️ RESEARCH BOX
**Date**: 2025-12-15
**Verdict**: **NEUTRAL (-0.70% Mixed, +0.42% C7-only)** — research box 維持default OFF
**Motivation**: Phase 14tcache intrusiveが NEUTRAL だったため、intrusive を増やさず、既存 `TinyUnifiedCache.slots[]` を FIFO ring から LIFO stack に変更して局所性改善を狙った。
**Results**:
| Workload | LIFO=0 (FIFO) | LIFO=1 (LIFO) | Delta |
|---------|----------|----------|-------|
| Mixed (161024B) | 52,965,966 | 52,593,948 | **-0.70%** |
| C7-only (10252048B) | 78,010,783 | 78,335,509 | **+0.42%** |
**Conclusion**:
- LIFO への変更は期待した効果なしMixed で劣化、C7 で微改善だが両方 GO 閾値未達)
- モード判定分岐オーバーヘッド(`tiny_unified_lifo_enabled()`)が局所性改善を相殺
- 既存 FIFO ring 実装が既に十分最適化されている
**Root causes**:
1. Entry-point mode check overhead (`tiny_unified_lifo_enabled()` call)
2. Minimal LIFO vs FIFO locality delta in practice (cache warming mitigates)
3. Existing FIFO ring already well-optimized
**Bonus**: LTO bug fix for `tiny_c7_preserve_header_enabled()` (Phase 13/14 latent issue)
**Refs**:
- A/B results: `docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_AB_TEST_RESULTS.md`
- Design: `docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_DESIGN.md`
- Instructions: `docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_NEXT_INSTRUCTIONS.md`
---
### Phase 14-15 Summary: Pointer-Chase & Cache-Shape Research ⚠️
**Conclusion**: 両 Phase とも NEUTRAL研究箱として凍結
| Phase | Approach | Mixed Delta | C7 Delta | Verdict |
|-------|----------|-------------|----------|---------|
| 14 v1 | tcache (free-side only) | +0.20% | N/A | NEUTRAL |
| 14 v2 | tcache (alloc+free) | +0.08% | -0.39% | NEUTRAL |
| 15 v1 | FIFO→LIFO (array cache) | -0.70% | +0.42% | NEUTRAL |
**教訓**:
- Pointer-chase 削減も cache 形状変更も、現状の TLS array cache に対して有意な改善を生まない
- 次の mimalloc gap約 2.4x)を埋めるには、別次元のアプローチが必要
## 更新メモ2025-12-14 Phase 5 E5-3 Analysis - Strategic Pivot
### Phase 5 E5-3: Candidate Analysis & Strategic Recommendations ⚠️ DEFER (2025-12-14)

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@ -218,12 +218,12 @@ LDFLAGS += $(EXTRA_LDFLAGS)
# Targets
TARGET = test_hakmem
OBJS_BASE = hakmem.o hakmem_config.o hakmem_tiny_config.o hakmem_ucb1.o hakmem_bigcache.o hakmem_pool.o hakmem_l25_pool.o hakmem_site_rules.o hakmem_tiny.o core/box/ss_allocation_box.o superslab_stats.o superslab_cache.o superslab_ace.o superslab_slab.o superslab_backend.o core/superslab_head_stub.o hakmem_smallmid.o tiny_sticky.o tiny_remote.o tiny_publish.o tiny_debug_ring.o hakmem_tiny_magazine.o hakmem_tiny_stats.o hakmem_tiny_sfc.o hakmem_tiny_query.o hakmem_tiny_rss.o hakmem_tiny_registry.o hakmem_tiny_remote_target.o hakmem_tiny_bg_spill.o tiny_adaptive_sizing.o hakmem_super_registry.o hakmem_shared_pool.o hakmem_shared_pool_acquire.o hakmem_shared_pool_release.o hakmem_elo.o hakmem_batch.o hakmem_p2.o hakmem_sizeclass_dist.o hakmem_evo.o hakmem_debug.o hakmem_sys.o hakmem_whale.o hakmem_policy.o hakmem_ace.o hakmem_ace_stats.o hakmem_prof.o hakmem_learner.o hakmem_size_hist.o hakmem_learn_log.o hakmem_syscall.o hakmem_ace_metrics.o hakmem_ace_ucb1.o hakmem_ace_controller.o tiny_fastcache.o core/box/superslab_expansion_box.o core/box/integrity_box.o core/box/free_publish_box.o core/box/mailbox_box.o core/box/front_gate_box.o core/box/front_gate_classifier.o core/box/capacity_box.o core/box/carve_push_box.o core/box/prewarm_box.o core/box/ss_hot_prewarm_box.o core/box/front_metrics_box.o core/box/bench_fast_box.o core/box/ss_addr_map_box.o core/box/ss_pt_impl.o core/box/slab_recycling_box.o core/box/pagefault_telemetry_box.o core/box/tiny_sizeclass_hist_box.o core/box/tiny_env_box.o core/box/tiny_route_box.o core/box/free_front_v3_env_box.o core/box/free_path_stats_box.o core/box/free_dispatch_stats_box.o core/box/free_cold_shape_env_box.o core/box/free_cold_shape_stats_box.o core/box/alloc_gate_stats_box.o core/box/tiny_c6_ultra_free_box.o core/box/tiny_c5_ultra_free_box.o core/box/tiny_c4_ultra_free_box.o core/box/tiny_ultra_tls_box.o core/box/tiny_page_box.o core/box/tiny_class_policy_box.o core/box/tiny_class_stats_box.o core/box/tiny_policy_learner_box.o core/box/ss_budget_box.o core/box/tiny_mem_stats_box.o core/box/c7_meta_used_counter_box.o core/box/tiny_static_route_box.o core/box/tiny_metadata_cache_hot_box.o core/box/wrapper_env_box.o core/box/free_wrapper_env_snapshot_box.o core/box/malloc_wrapper_env_snapshot_box.o core/box/madvise_guard_box.o core/box/libm_reloc_guard_box.o core/box/ptr_trace_box.o core/box/link_missing_stubs.o core/box/super_reg_box.o core/box/shared_pool_box.o core/box/remote_side_box.o core/box/hakmem_env_snapshot_box.o core/box/tiny_c7_preserve_header_env_box.o core/box/tiny_tcache_env_box.o core/page_arena.o core/front/tiny_unified_cache.o core/tiny_alloc_fast_push.o core/tiny_c7_ultra_segment.o core/tiny_c7_ultra.o core/link_stubs.o core/tiny_failfast.o core/tiny_destructors.o core/smallobject_hotbox_v3.o core/smallobject_hotbox_v4.o core/smallobject_hotbox_v5.o core/smallsegment_v5.o core/smallobject_cold_iface_v5.o core/smallsegment_v6.o core/smallobject_cold_iface_v6.o core/smallobject_core_v6.o core/region_id_v6.o core/smallsegment_v7.o core/smallobject_cold_iface_v7.o core/mid_hotbox_v3.o core/smallobject_policy_v7.o core/smallobject_segment_mid_v3.o core/smallobject_cold_iface_mid_v3.o core/smallobject_stats_mid_v3.o core/smallobject_learner_v2.o core/smallobject_mid_v35.o
OBJS_BASE = hakmem.o hakmem_config.o hakmem_tiny_config.o hakmem_ucb1.o hakmem_bigcache.o hakmem_pool.o hakmem_l25_pool.o hakmem_site_rules.o hakmem_tiny.o core/box/ss_allocation_box.o superslab_stats.o superslab_cache.o superslab_ace.o superslab_slab.o superslab_backend.o core/superslab_head_stub.o hakmem_smallmid.o tiny_sticky.o tiny_remote.o tiny_publish.o tiny_debug_ring.o hakmem_tiny_magazine.o hakmem_tiny_stats.o hakmem_tiny_sfc.o hakmem_tiny_query.o hakmem_tiny_rss.o hakmem_tiny_registry.o hakmem_tiny_remote_target.o hakmem_tiny_bg_spill.o tiny_adaptive_sizing.o hakmem_super_registry.o hakmem_shared_pool.o hakmem_shared_pool_acquire.o hakmem_shared_pool_release.o hakmem_elo.o hakmem_batch.o hakmem_p2.o hakmem_sizeclass_dist.o hakmem_evo.o hakmem_debug.o hakmem_sys.o hakmem_whale.o hakmem_policy.o hakmem_ace.o hakmem_ace_stats.o hakmem_prof.o hakmem_learner.o hakmem_size_hist.o hakmem_learn_log.o hakmem_syscall.o hakmem_ace_metrics.o hakmem_ace_ucb1.o hakmem_ace_controller.o tiny_fastcache.o core/box/superslab_expansion_box.o core/box/integrity_box.o core/box/free_publish_box.o core/box/mailbox_box.o core/box/front_gate_box.o core/box/front_gate_classifier.o core/box/capacity_box.o core/box/carve_push_box.o core/box/prewarm_box.o core/box/ss_hot_prewarm_box.o core/box/front_metrics_box.o core/box/bench_fast_box.o core/box/ss_addr_map_box.o core/box/ss_pt_impl.o core/box/slab_recycling_box.o core/box/pagefault_telemetry_box.o core/box/tiny_sizeclass_hist_box.o core/box/tiny_env_box.o core/box/tiny_route_box.o core/box/free_front_v3_env_box.o core/box/free_path_stats_box.o core/box/free_dispatch_stats_box.o core/box/free_cold_shape_env_box.o core/box/free_cold_shape_stats_box.o core/box/alloc_gate_stats_box.o core/box/tiny_c6_ultra_free_box.o core/box/tiny_c5_ultra_free_box.o core/box/tiny_c4_ultra_free_box.o core/box/tiny_ultra_tls_box.o core/box/tiny_page_box.o core/box/tiny_class_policy_box.o core/box/tiny_class_stats_box.o core/box/tiny_policy_learner_box.o core/box/ss_budget_box.o core/box/tiny_mem_stats_box.o core/box/c7_meta_used_counter_box.o core/box/tiny_static_route_box.o core/box/tiny_metadata_cache_hot_box.o core/box/wrapper_env_box.o core/box/free_wrapper_env_snapshot_box.o core/box/malloc_wrapper_env_snapshot_box.o core/box/madvise_guard_box.o core/box/libm_reloc_guard_box.o core/box/ptr_trace_box.o core/box/link_missing_stubs.o core/box/super_reg_box.o core/box/shared_pool_box.o core/box/remote_side_box.o core/box/hakmem_env_snapshot_box.o core/box/tiny_c7_preserve_header_env_box.o core/box/tiny_tcache_env_box.o core/box/tiny_unified_lifo_env_box.o core/page_arena.o core/front/tiny_unified_cache.o core/tiny_alloc_fast_push.o core/tiny_c7_ultra_segment.o core/tiny_c7_ultra.o core/link_stubs.o core/tiny_failfast.o core/tiny_destructors.o core/smallobject_hotbox_v3.o core/smallobject_hotbox_v4.o core/smallobject_hotbox_v5.o core/smallsegment_v5.o core/smallobject_cold_iface_v5.o core/smallsegment_v6.o core/smallobject_cold_iface_v6.o core/smallobject_core_v6.o core/region_id_v6.o core/smallsegment_v7.o core/smallobject_cold_iface_v7.o core/mid_hotbox_v3.o core/smallobject_policy_v7.o core/smallobject_segment_mid_v3.o core/smallobject_cold_iface_mid_v3.o core/smallobject_stats_mid_v3.o core/smallobject_learner_v2.o core/smallobject_mid_v35.o
OBJS = $(OBJS_BASE)
# Shared library
SHARED_LIB = libhakmem.so
SHARED_OBJS = hakmem_shared.o hakmem_config_shared.o hakmem_tiny_config_shared.o hakmem_ucb1_shared.o hakmem_bigcache_shared.o hakmem_pool_shared.o hakmem_l25_pool_shared.o hakmem_site_rules_shared.o hakmem_tiny_shared.o core/box/ss_allocation_box_shared.o superslab_stats_shared.o superslab_cache_shared.o superslab_ace_shared.o superslab_slab_shared.o superslab_backend_shared.o core/superslab_head_stub_shared.o hakmem_smallmid_shared.o core/box/superslab_expansion_box_shared.o core/box/integrity_box_shared.o core/box/mailbox_box_shared.o core/box/front_gate_box_shared.o core/box/front_gate_classifier_shared.o core/box/free_publish_box_shared.o core/box/capacity_box_shared.o core/box/carve_push_box_shared.o core/box/prewarm_box_shared.o core/box/ss_hot_prewarm_box_shared.o core/box/front_metrics_box_shared.o core/box/bench_fast_box_shared.o core/box/ss_addr_map_box_shared.o core/box/ss_pt_impl_shared.o core/box/slab_recycling_box_shared.o core/box/pagefault_telemetry_box_shared.o core/box/tiny_sizeclass_hist_box_shared.o core/box/tiny_env_box_shared.o core/box/tiny_route_box_shared.o core/box/free_front_v3_env_box_shared.o core/box/free_path_stats_box_shared.o core/box/free_dispatch_stats_box_shared.o core/box/alloc_gate_stats_box_shared.o core/box/tiny_page_box_shared.o core/box/tiny_class_policy_box_shared.o core/box/tiny_class_stats_box_shared.o core/box/tiny_policy_learner_box_shared.o core/box/ss_budget_box_shared.o core/box/tiny_mem_stats_box_shared.o core/box/wrapper_env_box_shared.o core/box/free_wrapper_env_snapshot_box_shared.o core/box/malloc_wrapper_env_snapshot_box_shared.o core/box/madvise_guard_box_shared.o core/box/libm_reloc_guard_box_shared.o core/box/hakmem_env_snapshot_box_shared.o core/box/tiny_c7_preserve_header_env_box_shared.o core/box/tiny_tcache_env_box_shared.o core/page_arena_shared.o core/front/tiny_unified_cache_shared.o core/tiny_alloc_fast_push_shared.o core/tiny_c7_ultra_segment_shared.o core/tiny_c7_ultra_shared.o core/link_stubs_shared.o core/tiny_failfast_shared.o tiny_sticky_shared.o tiny_remote_shared.o tiny_publish_shared.o tiny_debug_ring_shared.o hakmem_tiny_magazine_shared.o hakmem_tiny_stats_shared.o hakmem_tiny_sfc_shared.o hakmem_tiny_query_shared.o hakmem_tiny_rss_shared.o hakmem_tiny_registry_shared.o hakmem_tiny_remote_target_shared.o hakmem_tiny_bg_spill_shared.o tiny_adaptive_sizing_shared.o hakmem_super_registry_shared.o hakmem_shared_pool_shared.o hakmem_shared_pool_acquire_shared.o hakmem_shared_pool_release_shared.o hakmem_elo_shared.o hakmem_batch_shared.o hakmem_p2_shared.o hakmem_sizeclass_dist_shared.o hakmem_evo_shared.o hakmem_debug_shared.o hakmem_sys_shared.o hakmem_whale_shared.o hakmem_policy_shared.o hakmem_ace_shared.o hakmem_ace_stats_shared.o hakmem_ace_controller_shared.o hakmem_ace_metrics_shared.o hakmem_ace_ucb1_shared.o hakmem_prof_shared.o hakmem_learner_shared.o hakmem_size_hist_shared.o hakmem_learn_log_shared.o hakmem_syscall_shared.o tiny_fastcache_shared.o core/box/super_reg_box_shared.o core/box/shared_pool_box_shared.o core/box/remote_side_box_shared.o core/tiny_destructors_shared.o
SHARED_OBJS = hakmem_shared.o hakmem_config_shared.o hakmem_tiny_config_shared.o hakmem_ucb1_shared.o hakmem_bigcache_shared.o hakmem_pool_shared.o hakmem_l25_pool_shared.o hakmem_site_rules_shared.o hakmem_tiny_shared.o core/box/ss_allocation_box_shared.o superslab_stats_shared.o superslab_cache_shared.o superslab_ace_shared.o superslab_slab_shared.o superslab_backend_shared.o core/superslab_head_stub_shared.o hakmem_smallmid_shared.o core/box/superslab_expansion_box_shared.o core/box/integrity_box_shared.o core/box/mailbox_box_shared.o core/box/front_gate_box_shared.o core/box/front_gate_classifier_shared.o core/box/free_publish_box_shared.o core/box/capacity_box_shared.o core/box/carve_push_box_shared.o core/box/prewarm_box_shared.o core/box/ss_hot_prewarm_box_shared.o core/box/front_metrics_box_shared.o core/box/bench_fast_box_shared.o core/box/ss_addr_map_box_shared.o core/box/ss_pt_impl_shared.o core/box/slab_recycling_box_shared.o core/box/pagefault_telemetry_box_shared.o core/box/tiny_sizeclass_hist_box_shared.o core/box/tiny_env_box_shared.o core/box/tiny_route_box_shared.o core/box/free_front_v3_env_box_shared.o core/box/free_path_stats_box_shared.o core/box/free_dispatch_stats_box_shared.o core/box/alloc_gate_stats_box_shared.o core/box/tiny_page_box_shared.o core/box/tiny_class_policy_box_shared.o core/box/tiny_class_stats_box_shared.o core/box/tiny_policy_learner_box_shared.o core/box/ss_budget_box_shared.o core/box/tiny_mem_stats_box_shared.o core/box/wrapper_env_box_shared.o core/box/free_wrapper_env_snapshot_box_shared.o core/box/malloc_wrapper_env_snapshot_box_shared.o core/box/madvise_guard_box_shared.o core/box/libm_reloc_guard_box_shared.o core/box/hakmem_env_snapshot_box_shared.o core/box/tiny_c7_preserve_header_env_box_shared.o core/box/tiny_tcache_env_box_shared.o core/box/tiny_unified_lifo_env_box_shared.o core/page_arena_shared.o core/front/tiny_unified_cache_shared.o core/tiny_alloc_fast_push_shared.o core/tiny_c7_ultra_segment_shared.o core/tiny_c7_ultra_shared.o core/link_stubs_shared.o core/tiny_failfast_shared.o tiny_sticky_shared.o tiny_remote_shared.o tiny_publish_shared.o tiny_debug_ring_shared.o hakmem_tiny_magazine_shared.o hakmem_tiny_stats_shared.o hakmem_tiny_sfc_shared.o hakmem_tiny_query_shared.o hakmem_tiny_rss_shared.o hakmem_tiny_registry_shared.o hakmem_tiny_remote_target_shared.o hakmem_tiny_bg_spill_shared.o tiny_adaptive_sizing_shared.o hakmem_super_registry_shared.o hakmem_shared_pool_shared.o hakmem_shared_pool_acquire_shared.o hakmem_shared_pool_release_shared.o hakmem_elo_shared.o hakmem_batch_shared.o hakmem_p2_shared.o hakmem_sizeclass_dist_shared.o hakmem_evo_shared.o hakmem_debug_shared.o hakmem_sys_shared.o hakmem_whale_shared.o hakmem_policy_shared.o hakmem_ace_shared.o hakmem_ace_stats_shared.o hakmem_ace_controller_shared.o hakmem_ace_metrics_shared.o hakmem_ace_ucb1_shared.o hakmem_prof_shared.o hakmem_learner_shared.o hakmem_size_hist_shared.o hakmem_learn_log_shared.o hakmem_syscall_shared.o tiny_fastcache_shared.o core/box/super_reg_box_shared.o core/box/shared_pool_box_shared.o core/box/remote_side_box_shared.o core/tiny_destructors_shared.o
# Pool TLS Phase 1 (enable with POOL_TLS_PHASE1=1)
ifeq ($(POOL_TLS_PHASE1),1)
@ -427,7 +427,7 @@ test-box-refactor: box-refactor
./larson_hakmem 10 8 128 1024 1 12345 4
# Phase 4: Tiny Pool benchmarks (properly linked with hakmem)
TINY_BENCH_OBJS_BASE = hakmem.o hakmem_config.o hakmem_tiny_config.o hakmem_ucb1.o hakmem_bigcache.o hakmem_pool.o hakmem_l25_pool.o hakmem_site_rules.o hakmem_tiny.o core/box/ss_allocation_box.o superslab_stats.o superslab_cache.o superslab_ace.o superslab_slab.o superslab_backend.o core/superslab_head_stub.o hakmem_smallmid.o core/box/superslab_expansion_box.o core/box/integrity_box.o core/box/mailbox_box.o core/box/front_gate_box.o core/box/front_gate_classifier.o core/box/free_publish_box.o core/box/capacity_box.o core/box/carve_push_box.o core/box/prewarm_box.o core/box/ss_hot_prewarm_box.o core/box/front_metrics_box.o core/box/bench_fast_box.o core/box/ss_addr_map_box.o core/box/ss_pt_impl.o core/box/slab_recycling_box.o core/box/pagefault_telemetry_box.o core/box/tiny_sizeclass_hist_box.o core/box/tiny_env_box.o core/box/tiny_route_box.o core/box/free_front_v3_env_box.o core/box/free_path_stats_box.o core/box/free_dispatch_stats_box.o core/box/free_cold_shape_env_box.o core/box/free_cold_shape_stats_box.o core/box/alloc_gate_stats_box.o core/box/tiny_c6_ultra_free_box.o core/box/tiny_c5_ultra_free_box.o core/box/tiny_c4_ultra_free_box.o core/box/tiny_ultra_tls_box.o core/box/tiny_page_box.o core/box/tiny_class_policy_box.o core/box/tiny_class_stats_box.o core/box/tiny_policy_learner_box.o core/box/ss_budget_box.o core/box/tiny_mem_stats_box.o core/box/c7_meta_used_counter_box.o core/box/tiny_static_route_box.o core/box/tiny_metadata_cache_hot_box.o core/box/wrapper_env_box.o core/box/free_wrapper_env_snapshot_box.o core/box/malloc_wrapper_env_snapshot_box.o core/box/madvise_guard_box.o core/box/libm_reloc_guard_box.o core/box/ptr_trace_box.o core/box/link_missing_stubs.o core/box/super_reg_box.o core/box/shared_pool_box.o core/box/remote_side_box.o core/box/tiny_free_route_cache_env_box.o core/box/hakmem_env_snapshot_box.o core/box/tiny_c7_preserve_header_env_box.o core/box/tiny_tcache_env_box.o core/page_arena.o core/front/tiny_unified_cache.o tiny_sticky.o tiny_remote.o tiny_publish.o tiny_debug_ring.o hakmem_tiny_magazine.o hakmem_tiny_stats.o hakmem_tiny_sfc.o hakmem_tiny_query.o hakmem_tiny_rss.o hakmem_tiny_registry.o hakmem_tiny_remote_target.o hakmem_tiny_bg_spill.o tiny_adaptive_sizing.o hakmem_super_registry.o hakmem_shared_pool.o hakmem_shared_pool_acquire.o hakmem_shared_pool_release.o hakmem_elo.o hakmem_batch.o hakmem_p2.o hakmem_sizeclass_dist.o hakmem_evo.o hakmem_debug.o hakmem_sys.o hakmem_whale.o hakmem_policy.o hakmem_ace.o hakmem_ace_stats.o hakmem_prof.o hakmem_learner.o hakmem_size_hist.o hakmem_learn_log.o hakmem_syscall.o hakmem_ace_metrics.o hakmem_ace_ucb1.o hakmem_ace_controller.o tiny_fastcache.o core/tiny_alloc_fast_push.o core/tiny_c7_ultra_segment.o core/tiny_c7_ultra.o core/link_stubs.o core/tiny_failfast.o core/tiny_destructors.o core/smallobject_hotbox_v3.o core/smallobject_hotbox_v4.o core/smallobject_hotbox_v5.o core/smallsegment_v5.o core/smallobject_cold_iface_v5.o core/smallsegment_v6.o core/smallobject_cold_iface_v6.o core/smallobject_core_v6.o core/region_id_v6.o core/smallsegment_v7.o core/smallobject_cold_iface_v7.o core/mid_hotbox_v3.o core/smallobject_policy_v7.o core/smallobject_segment_mid_v3.o core/smallobject_cold_iface_mid_v3.o core/smallobject_stats_mid_v3.o core/smallobject_learner_v2.o core/smallobject_mid_v35.o
TINY_BENCH_OBJS_BASE = hakmem.o hakmem_config.o hakmem_tiny_config.o hakmem_ucb1.o hakmem_bigcache.o hakmem_pool.o hakmem_l25_pool.o hakmem_site_rules.o hakmem_tiny.o core/box/ss_allocation_box.o superslab_stats.o superslab_cache.o superslab_ace.o superslab_slab.o superslab_backend.o core/superslab_head_stub.o hakmem_smallmid.o core/box/superslab_expansion_box.o core/box/integrity_box.o core/box/mailbox_box.o core/box/front_gate_box.o core/box/front_gate_classifier.o core/box/free_publish_box.o core/box/capacity_box.o core/box/carve_push_box.o core/box/prewarm_box.o core/box/ss_hot_prewarm_box.o core/box/front_metrics_box.o core/box/bench_fast_box.o core/box/ss_addr_map_box.o core/box/ss_pt_impl.o core/box/slab_recycling_box.o core/box/pagefault_telemetry_box.o core/box/tiny_sizeclass_hist_box.o core/box/tiny_env_box.o core/box/tiny_route_box.o core/box/free_front_v3_env_box.o core/box/free_path_stats_box.o core/box/free_dispatch_stats_box.o core/box/free_cold_shape_env_box.o core/box/free_cold_shape_stats_box.o core/box/alloc_gate_stats_box.o core/box/tiny_c6_ultra_free_box.o core/box/tiny_c5_ultra_free_box.o core/box/tiny_c4_ultra_free_box.o core/box/tiny_ultra_tls_box.o core/box/tiny_page_box.o core/box/tiny_class_policy_box.o core/box/tiny_class_stats_box.o core/box/tiny_policy_learner_box.o core/box/ss_budget_box.o core/box/tiny_mem_stats_box.o core/box/c7_meta_used_counter_box.o core/box/tiny_static_route_box.o core/box/tiny_metadata_cache_hot_box.o core/box/wrapper_env_box.o core/box/free_wrapper_env_snapshot_box.o core/box/malloc_wrapper_env_snapshot_box.o core/box/madvise_guard_box.o core/box/libm_reloc_guard_box.o core/box/ptr_trace_box.o core/box/link_missing_stubs.o core/box/super_reg_box.o core/box/shared_pool_box.o core/box/remote_side_box.o core/box/tiny_free_route_cache_env_box.o core/box/hakmem_env_snapshot_box.o core/box/tiny_c7_preserve_header_env_box.o core/box/tiny_tcache_env_box.o core/box/tiny_unified_lifo_env_box.o core/page_arena.o core/front/tiny_unified_cache.o tiny_sticky.o tiny_remote.o tiny_publish.o tiny_debug_ring.o hakmem_tiny_magazine.o hakmem_tiny_stats.o hakmem_tiny_sfc.o hakmem_tiny_query.o hakmem_tiny_rss.o hakmem_tiny_registry.o hakmem_tiny_remote_target.o hakmem_tiny_bg_spill.o tiny_adaptive_sizing.o hakmem_super_registry.o hakmem_shared_pool.o hakmem_shared_pool_acquire.o hakmem_shared_pool_release.o hakmem_elo.o hakmem_batch.o hakmem_p2.o hakmem_sizeclass_dist.o hakmem_evo.o hakmem_debug.o hakmem_sys.o hakmem_whale.o hakmem_policy.o hakmem_ace.o hakmem_ace_stats.o hakmem_prof.o hakmem_learner.o hakmem_size_hist.o hakmem_learn_log.o hakmem_syscall.o hakmem_ace_metrics.o hakmem_ace_ucb1.o hakmem_ace_controller.o tiny_fastcache.o core/tiny_alloc_fast_push.o core/tiny_c7_ultra_segment.o core/tiny_c7_ultra.o core/link_stubs.o core/tiny_failfast.o core/tiny_destructors.o core/smallobject_hotbox_v3.o core/smallobject_hotbox_v4.o core/smallobject_hotbox_v5.o core/smallsegment_v5.o core/smallobject_cold_iface_v5.o core/smallsegment_v6.o core/smallobject_cold_iface_v6.o core/smallobject_core_v6.o core/region_id_v6.o core/smallsegment_v7.o core/smallobject_cold_iface_v7.o core/mid_hotbox_v3.o core/smallobject_policy_v7.o core/smallobject_segment_mid_v3.o core/smallobject_cold_iface_mid_v3.o core/smallobject_stats_mid_v3.o core/smallobject_learner_v2.o core/smallobject_mid_v35.o
TINY_BENCH_OBJS = $(TINY_BENCH_OBJS_BASE)
ifeq ($(POOL_TLS_PHASE1),1)
TINY_BENCH_OBJS += pool_tls.o pool_refill.o core/pool_tls_arena.o pool_tls_registry.o pool_tls_remote.o

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@ -12,6 +12,7 @@
#include "box/tiny_free_route_cache_env_box.h" // tiny_free_static_route_refresh_from_env (Phase 8)
#include "box/tiny_c7_preserve_header_env_box.h" // tiny_c7_preserve_header_env_refresh_from_env (Phase 13 v1)
#include "box/tiny_tcache_env_box.h" // tiny_tcache_env_refresh_from_env (Phase 14 v1)
#include "box/tiny_unified_lifo_env_box.h" // tiny_unified_lifo_env_refresh_from_env (Phase 15 v1)
#endif
// env が未設定のときだけ既定値を入れる
@ -190,5 +191,7 @@ static inline void bench_apply_profile(void) {
tiny_c7_preserve_header_env_refresh_from_env();
// Phase 14 v1: Sync tcache ENV cache after bench_profile putenv defaults.
tiny_tcache_env_refresh_from_env();
// Phase 15 v1: Sync LIFO ENV cache after bench_profile putenv defaults.
tiny_unified_lifo_env_refresh_from_env();
#endif
}

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@ -39,6 +39,19 @@ int tiny_c7_preserve_header_env_init(void) {
return enabled;
}
// ============================================================================
// Hot Path (LTO Fallback)
// ============================================================================
// LTO fallback: Non-inline version for cases where LTO can't inline
int tiny_c7_preserve_header_enabled(void) {
int val = atomic_load_explicit(&g_tiny_c7_preserve_header_enabled, memory_order_relaxed);
if (__builtin_expect(val == -1, 0)) {
val = tiny_c7_preserve_header_env_init();
}
return val;
}
// ============================================================================
// Refresh (Cold Path, called from bench_profile)
// ============================================================================

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@ -44,22 +44,13 @@
extern _Atomic int g_tiny_c7_preserve_header_enabled;
// ============================================================================
// Hot Inline API (L0)
// Hot API (L0)
// ============================================================================
// Check if C7 preserve header is enabled
// Returns: 1 if enabled, 0 if disabled
static inline int tiny_c7_preserve_header_enabled(void) {
int val = atomic_load_explicit(&g_tiny_c7_preserve_header_enabled, memory_order_relaxed);
if (__builtin_expect(val == -1, 0)) {
// Lazy init: read ENV once
extern int tiny_c7_preserve_header_env_init(void);
val = tiny_c7_preserve_header_env_init();
}
return val;
}
// Note: Implementation in .c file (non-inline for LTO compatibility)
extern int tiny_c7_preserve_header_enabled(void);
// ============================================================================
// Cold API (L2)

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@ -30,6 +30,7 @@
#include "../tiny_region_id.h"
#include "../front/tiny_unified_cache.h" // For TinyUnifiedCache
#include "tiny_header_box.h" // Phase 5 E5-2: For tiny_header_finalize_alloc
#include "tiny_unified_lifo_box.h" // Phase 15 v1: UnifiedCache FIFO→LIFO
// ============================================================================
// Branch Prediction Macros (Pointer Safety - Prediction Hints)
@ -107,12 +108,34 @@
//
__attribute__((always_inline))
static inline void* tiny_hot_alloc_fast(int class_idx) {
// Phase 15 v1: Mode check at entry (once per call, not scattered in hot path)
int lifo_mode = tiny_unified_lifo_enabled();
extern __thread TinyUnifiedCache g_unified_cache[];
// TLS cache access (1 cache miss)
// NOTE: Range check removed - caller (hak_tiny_size_to_class) guarantees valid class_idx
TinyUnifiedCache* cache = &g_unified_cache[class_idx];
// Phase 15 v1: LIFO vs FIFO mode switch
if (lifo_mode) {
// === LIFO MODE: Stack-based (LIFO) ===
// Try pop from stack (tail is stack depth)
void* base = unified_cache_try_pop_lifo(class_idx);
if (__builtin_expect(base != NULL, 1)) {
TINY_HOT_METRICS_HIT(class_idx);
#if HAKMEM_TINY_HEADER_CLASSIDX
return tiny_header_finalize_alloc(base, class_idx);
#else
return base;
#endif
}
// LIFO miss → fall through to cold path
TINY_HOT_METRICS_MISS(class_idx);
return NULL;
}
// === FIFO MODE: Ring-based (existing) ===
// Branch 1: Cache empty check (LIKELY hit)
// Hot path: cache has objects (head != tail)
// Cold path: cache empty (head == tail) → refill needed
@ -164,12 +187,35 @@ static inline void* tiny_hot_alloc_fast(int class_idx) {
//
__attribute__((always_inline))
static inline int tiny_hot_free_fast(int class_idx, void* base) {
// Phase 15 v1: Mode check at entry (once per call, not scattered in hot path)
int lifo_mode = tiny_unified_lifo_enabled();
extern __thread TinyUnifiedCache g_unified_cache[];
// TLS cache access (1 cache miss)
// NOTE: Range check removed - caller guarantees valid class_idx
TinyUnifiedCache* cache = &g_unified_cache[class_idx];
// Phase 15 v1: LIFO vs FIFO mode switch
if (lifo_mode) {
// === LIFO MODE: Stack-based (LIFO) ===
// Try push to stack (tail is stack depth)
if (unified_cache_try_push_lifo(class_idx, base)) {
#if !HAKMEM_BUILD_RELEASE
extern __thread uint64_t g_unified_cache_push[];
g_unified_cache_push[class_idx]++;
#endif
return 1; // SUCCESS
}
// LIFO overflow → fall through to cold path
#if !HAKMEM_BUILD_RELEASE
extern __thread uint64_t g_unified_cache_full[];
g_unified_cache_full[class_idx]++;
#endif
return 0; // FULL
}
// === FIFO MODE: Ring-based (existing) ===
// Calculate next tail (for full check)
uint16_t next_tail = (cache->tail + 1) & cache->mask;

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@ -0,0 +1,121 @@
// ============================================================================
// Phase 15 v1: Tiny Unified LIFO Box (L1) - LIFO Stack Operations
// ============================================================================
//
// Purpose: LIFO (stack) operations for UnifiedCache
//
// Design: docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_DESIGN.md
//
// Strategy:
// - Reuse existing TinyUnifiedCache.slots[] array
// - Treat `tail` as stack top (depth)
// - Treat `head` as unused (always 0)
// - No wrap-around (`mask` unused)
//
// Invariants:
// - 0 <= tail <= capacity (stack depth)
// - head == 0 (unused in LIFO mode)
// - LIFO and FIFO modes are mutually exclusive
//
// API:
// unified_cache_try_pop_lifo(class_idx) -> void* (BASE or NULL)
// unified_cache_try_push_lifo(class_idx, base) -> int (1=success, 0=full)
//
// Safety:
// - Debug: assert tail <= capacity
// - Release: fast path, no checks
//
// ============================================================================
#ifndef TINY_UNIFIED_LIFO_BOX_H
#define TINY_UNIFIED_LIFO_BOX_H
#include <stdint.h>
#include <assert.h>
#include "../hakmem_build_flags.h"
#include "../hakmem_tiny_config.h" // TINY_NUM_CLASSES
#include "../front/tiny_unified_cache.h" // TinyUnifiedCache
#include "tiny_unified_lifo_env_box.h" // tiny_unified_lifo_enabled
// ============================================================================
// LIFO Pop (Alloc Fast Path)
// ============================================================================
//
// Arguments:
// class_idx - Tiny class index (0-7)
//
// Returns:
// BASE pointer - Block from top of stack
// NULL - Stack empty
//
// Side effects:
// - Decrements tail (stack depth)
//
// LIFO semantics:
// - Pop from top of stack (tail - 1)
// - tail is "one past last element" (like vector.size())
//
__attribute__((always_inline))
static inline void* unified_cache_try_pop_lifo(int class_idx) {
extern __thread TinyUnifiedCache g_unified_cache[];
TinyUnifiedCache* cache = &g_unified_cache[class_idx];
// Empty check (tail == 0 means stack is empty)
if (__builtin_expect(cache->tail == 0, 0)) {
return NULL; // Empty
}
// Pop from top of stack (LIFO)
void* base = cache->slots[--cache->tail];
// Debug: validate stack depth
#if !HAKMEM_BUILD_RELEASE
assert(cache->tail <= cache->capacity);
#endif
return base; // HIT (BASE pointer)
}
// ============================================================================
// LIFO Push (Free Fast Path)
// ============================================================================
//
// Arguments:
// class_idx - Tiny class index (0-7)
// base - BASE pointer to freed block
//
// Returns:
// 1 - Block pushed to stack (success)
// 0 - Stack full (overflow)
//
// Side effects:
// - Increments tail (stack depth)
//
// LIFO semantics:
// - Push to top of stack (tail)
// - tail is "one past last element"
//
__attribute__((always_inline))
static inline int unified_cache_try_push_lifo(int class_idx, void* base) {
extern __thread TinyUnifiedCache g_unified_cache[];
TinyUnifiedCache* cache = &g_unified_cache[class_idx];
// Full check (tail == capacity means stack is full)
if (__builtin_expect(cache->tail >= cache->capacity, 0)) {
return 0; // Full
}
// Push to top of stack (LIFO)
cache->slots[cache->tail++] = base;
// Debug: validate stack depth
#if !HAKMEM_BUILD_RELEASE
assert(cache->tail <= cache->capacity);
#endif
return 1; // SUCCESS
}
#endif // TINY_UNIFIED_LIFO_BOX_H

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@ -0,0 +1,50 @@
// ============================================================================
// Phase 15 v1: Tiny Unified LIFO ENV Box (L0) - Implementation
// ============================================================================
#include "tiny_unified_lifo_env_box.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
// ============================================================================
// Global State
// ============================================================================
_Atomic int g_tiny_unified_lifo_enabled = -1;
// ============================================================================
// Init (Cold Path)
// ============================================================================
int tiny_unified_lifo_env_init(void) {
const char* env = getenv("HAKMEM_TINY_UNIFIED_LIFO");
int enabled = 0; // default: OFF (opt-in)
if (env && (env[0] == '1' || strcmp(env, "true") == 0 || strcmp(env, "TRUE") == 0)) {
enabled = 1;
}
// Cache result
atomic_store_explicit(&g_tiny_unified_lifo_enabled, enabled, memory_order_relaxed);
// Log once (stderr for immediate visibility)
if (enabled) {
const char msg[] = "[UNIFIED_LIFO] enabled\n";
ssize_t w = write(2, msg, sizeof(msg) - 1);
(void)w;
}
return enabled;
}
// ============================================================================
// Refresh (Cold Path, called from bench_profile)
// ============================================================================
void tiny_unified_lifo_env_refresh_from_env(void) {
// Reset to uninitialized state (-1)
// Next call to tiny_unified_lifo_enabled() will re-read ENV
atomic_store_explicit(&g_tiny_unified_lifo_enabled, -1, memory_order_relaxed);
}

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@ -0,0 +1,72 @@
// ============================================================================
// Phase 15 v1: Tiny Unified LIFO ENV Box (L0)
// ============================================================================
//
// Purpose: ENV gate for UnifiedCache FIFO→LIFO mode switch
//
// Design: docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_DESIGN.md
// Instructions: docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_NEXT_INSTRUCTIONS.md
//
// Strategy:
// - UnifiedCache の形状を FIFO ring → LIFO stack に変更
// - 既存 slots[] をそのまま使うintrusive nextptr なし)
// - tail を "top" として扱い、head は未使用
//
// ENV:
// HAKMEM_TINY_UNIFIED_LIFO=0/1 (default: 0, opt-in)
//
// API:
// tiny_unified_lifo_enabled() -> int
// tiny_unified_lifo_env_refresh_from_env()
//
// Box Theory:
// - L0: This file (ENV gate, reversible)
// - L1: tiny_unified_lifo_box.h (LIFO push/pop operations)
// - L2: tiny_front_hot_box.h (integration point)
//
// Safety:
// - ENV-gated (default OFF, opt-in)
// - Reversible (ENV toggle)
// - Mode switch requires cache drain/reset
//
// ============================================================================
#ifndef TINY_UNIFIED_LIFO_ENV_BOX_H
#define TINY_UNIFIED_LIFO_ENV_BOX_H
#include <stdatomic.h>
// ============================================================================
// Global State (L0)
// ============================================================================
// Cached state: -1 (uninitialized), 0 (disabled), 1 (enabled)
extern _Atomic int g_tiny_unified_lifo_enabled;
// ============================================================================
// Hot Inline API (L0)
// ============================================================================
// Check if LIFO mode is enabled
// Returns: 1 if enabled, 0 if disabled
static inline int tiny_unified_lifo_enabled(void) {
int val = atomic_load_explicit(&g_tiny_unified_lifo_enabled, memory_order_relaxed);
if (__builtin_expect(val == -1, 0)) {
// Lazy init: read ENV once
extern int tiny_unified_lifo_env_init(void);
val = tiny_unified_lifo_env_init();
}
return val;
}
// ============================================================================
// Cold API (L2)
// ============================================================================
// Refresh ENV cache (called from bench_profile after putenv)
// Note: Mode switch during runtime requires cache drain/reset
extern void tiny_unified_lifo_env_refresh_from_env(void);
#endif // TINY_UNIFIED_LIFO_ENV_BOX_H

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@ -129,3 +129,17 @@ scripts/verify_health_profiles.sh
- Rollback:
- `export HAKMEM_TINY_TCACHE=0`
---
## 6. 追加調査(やるなら最小 2 本だけ)
Phase 14 v2 が NEUTRAL の場合、これ以上 “cap 探索” を無制限に回すより、まず原因を 2 本に絞る:
1) **tcache hit 率の可視化TLS カウンタのみ、atomic 禁止)**
- `tiny_tcache_try_pop/push` の hit/miss/overflow を TLS で数え、Mixed/C7-only で “本当に hit しているか” を確認する。
2) **TLS-only nextptr wrapperfence なし)を tcache 専用に導入する v3**
- `tiny_next_load/store` は汎用 SSOT のため fence / header restore 分岐を含む。
- tcache は TLS-only なので、`tiny_nextptr_offset()` だけを使い、load/store は memcpy/直書きfenceなしにする “tcache専用 next” を L1 に閉じ込めて A/B。
上記 2 本が “当たらない” 場合は、Phase 14 系tcache 追加)は freeze を確定し、別の構造差metadata/segment/remote/footprintへ移る。

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@ -0,0 +1,83 @@
# Phase 15 v1: UnifiedCache FIFO→LIFO (Stack) A/B Test Results
**Date:** 2025-12-15
**Benchmark:** Mixed (161024B) + C7-only (10252048B) 10-run cleanenv
**Target:** Transform existing UnifiedCache from FIFO ring to LIFO stack
**Expected ROI:** +5-10% (design estimate, cache locality improvement)
**GO Threshold:** +1.0% mean improvement
---
## 1. Implementation Summary
Phase 15 v1 transforms the existing array-based UnifiedCache from FIFO (ring buffer) to LIFO (stack) layout.
**Key Changes:**
- **Patch 1**: L0 ENV gate box (`tiny_unified_lifo_env_box.{h,c}`)
- **Patch 2**: L1 LIFO operations (`tiny_unified_lifo_box.h`)
- **Patch 3**: Hot path integration (`tiny_front_hot_box.h` - alloc/free both)
- **Patch 4**: Makefile updates (added `.o` files)
- **Patch 5**: bench_profile.h refresh sync
**Design:**
- Reuses existing `TinyUnifiedCache.slots[]` array (no intrusive pointers)
- `tail` treated as stack top (depth), `head` unused (always 0)
- Mode check at function entry (once per call)
- No wrap-around (`mask` unused in LIFO mode)
**ENV Control:**
```bash
export HAKMEM_TINY_UNIFIED_LIFO=0 # Baseline (FIFO)
export HAKMEM_TINY_UNIFIED_LIFO=1 # Optimized (LIFO)
```
**Bonus Fix:**
- Discovered and fixed pre-existing LTO linkage bug for `tiny_c7_preserve_header_enabled()` (Phase 13/14 latent issue)
- Converted static inline to extern declaration + non-inline implementation
---
## 2. A/B Test Results
### Mixed (161024B):
- **Baseline (LIFO=0):** 52,965,966 ops/s
- **Optimized (LIFO=1):** 52,593,948 ops/s
- **Delta:** **-0.70%** (regression)
### C7-only (10252048B):
- **Baseline (LIFO=0):** 78,010,783 ops/s
- **Optimized (LIFO=1):** 78,335,509 ops/s
- **Delta:** **+0.42%** (slight improvement)
---
## 3. Verdict: NEUTRAL
**Result:** Mixed -0.70%, C7-only +0.42% (both below GO threshold)
**Comparison to Phase 14:**
- Phase 14 v1 (tcache free-side only): Mixed +0.20% (NEUTRAL)
- Phase 14 v2 (tcache alloc+free): Mixed +0.08%, C7-only -0.39% (NEUTRAL)
- Phase 15 v1 (FIFO→LIFO): Mixed -0.70%, C7-only +0.42% (NEUTRAL)
**Root Cause:**
1. **Mode check overhead**: Entry-point `tiny_unified_lifo_enabled()` call adds branch
2. **Minimal locality delta**: LIFO vs FIFO temporal locality difference is small in practice
3. **Existing optimization**: FIFO ring implementation already well-optimized
4. **Cache warming**: TLS cache pre-warming reduces locality sensitivity
---
## 4. Recommendation: Freeze as Research Box
**Decision:** Freeze Phase 15 v1 as research box (HAKMEM_TINY_UNIFIED_LIFO=0 default, OFF)
**Rationale:**
- Neither LIFO nor FIFO shows significant advantage
- Mode switching overhead outweighs potential locality gains
- Existing FIFO ring is simple and already fast
**Next:** Explore alternative approaches:
- Hybrid strategies (per-class mode selection)
- Batch operations (reduce per-call overhead)
- Hardware prefetch hints (explicit locality control)

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@ -0,0 +1,120 @@
# Phase 15: UnifiedCache FIFO→LIFO (Stack) v1 Design
**Date:** 2025-12-15
**Status:** DESIGN (next candidate)
---
## 0. Motivation (Why this next?)
Phase 14intrusive tcachev1/v2 は通電確認まで行ったが **NEUTRAL**
一方で system/mimalloc と比べると、Tiny の thread cache 形状は依然として最重要仮説のまま。
現行の `TinyUnifiedCache`**FIFO ring (head/tail + mask)**:
- pop/push が毎回 `head/tail``mask` の更新を行う
- “最近 free したブロック” を最優先で再利用できない(局所性が薄い)
glibc tcache / mimalloc 系の勝ちパターンは **LIFO** が多い。
Phase 15 は intrusivenextptrを増やさず、既存 `slots[]` 配列をそのまま使って
**FIFO→LIFOstack**へ形状変更し、命令数・局所性の両方で勝ち筋を狙う。
---
## 1. Design (Box Theory)
### 1.1 Boxes
```
L0: unified_cache_shape_env_box (ENV gate, reversible)
L1: unified_cache_lifo_box (push/pop LIFO only, no side effects)
L2: existing unified_cache (FIFO) (fallback / compatibility)
```
**境界は 1 箇所**:
- LIFO disabled → FIFO を使う
- LIFO enabled → LIFO を使う
(実装上は “同一関数内で分岐” になる可能性があるが、責務は箱で分ける)
---
## 2. API (minimal)
ENV:
- `HAKMEM_TINY_UNIFIED_LIFO=0/1` (default 0, opt-in)
L1 API内部用、static inline:
- `unified_cache_pop_lifo(int class_idx) -> BASE or NULL`
- `unified_cache_push_lifo(int class_idx, BASE) -> 1/0`
統合点(候補):
- `tiny_hot_alloc_fast()` / `tiny_hot_free_fast()`
- ここが “実ホットパス” で、FIFO/LIFO の差分を最も素直に測れる
- もしくは `unified_cache_pop()` / `unified_cache_push()`
- 既存 caller を増やさず広く効かせたい場合
---
## 3. Implementation sketch (concept)
### 3.1 LIFO state
`TinyUnifiedCache``top` を追加するのではなく、v1 では互換性優先:
- 既存の `head/tail` のうち **`tail` を “top” とみなす**stack depth
- `head` は常に 0または未使用
- `mask` は不要wrap-around しない)
LIFO push:
- if `tail < capacity`: `slots[tail++] = base`
LIFO pop:
- if `tail > 0`: `base = slots[--tail]`
FIFO とは並立できないため、モード切替時の整合は “drain/reset” を境界に置く)
### 3.2 Mode switch safety (Fail-Fast)
- LIFO ON へ切り替える際は `unified_cache_init()` 後に **各 class の `head/tail` を reset**empty扱い
- bench/profile では init 前に ENV が確定する前提だが、研究箱として “refresh” を持つなら
- refresh 時は切替を禁止(または drain/reset を強制)
---
## 4. A/B Plan (same binary)
Baseline:
```sh
HAKMEM_TINY_UNIFIED_LIFO=0 scripts/run_mixed_10_cleanenv.sh
```
Optimized:
```sh
HAKMEM_TINY_UNIFIED_LIFO=1 scripts/run_mixed_10_cleanenv.sh
```
追加で “局所性が効くか” を確認:
```sh
HAKMEM_BENCH_C7_ONLY=1 HAKMEM_TINY_UNIFIED_LIFO=0 scripts/run_mixed_10_cleanenv.sh
HAKMEM_BENCH_C7_ONLY=1 HAKMEM_TINY_UNIFIED_LIFO=1 scripts/run_mixed_10_cleanenv.sh
```
GO/NO-GO:
- GO: Mixed mean +1.0% 以上
- NO-GO: mean -1.0% 以下
- NEUTRAL: ±1.0%freeze
---
## 5. Risks
1) **mode 分岐の固定費**で相殺Phase 11/14 の再来)
→ 対策: “入口で 1 回だけ” 判定し、hot では分岐を増やさない(関数ポインタ or snapshot
2) **切替時の整合**FIFO state と LIFO state の互換なし)
→ 対策: refresh 時の切替は禁止 or drain/reset を境界 1 箇所に固定
3) **容量チューニング依存**
→ v1 はまず形状のみを変えて ROI を確認し、cap 探索は v2 へ分離

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@ -0,0 +1,98 @@
# Phase 15: UnifiedCache FIFO→LIFO (Stack) v1 — Next Instructions
設計: `docs/analysis/PHASE15_UNIFIEDCACHE_LIFO_1_DESIGN.md`
---
## 0. Status / Why now
- Phase 14 v1/v2intrusive tcache**NEUTRAL** → freezedefault OFF
- 次の狙いは intrusive を増やさず、既存 `slots[]` を使って **FIFO ring → LIFO stack** に変える(形状で命令数と局所性を取りに行く)
---
## 1. GO 条件
Mixed 10-runclean env:
- **GO**: mean +1.0% 以上
- **NO-GO**: mean -1.0% 以下
- **NEUTRAL**: ±1.0% → research box freeze
---
## 2. Patch 順(小さく積む)
### Patch 1: L0 ENV gate box戻せる
新規:
- `core/box/tiny_unified_lifo_env_box.{h,c}`
ENV:
- `HAKMEM_TINY_UNIFIED_LIFO=0/1`default 0
要件:
- hot path に `getenv()` を置かないcached
- bench_profile の `putenv()` 同期が必要なら refresh API を用意(ただし mode 切替の整合に注意)
### Patch 2: L1 LIFO 操作箱(副作用ゼロ)
新規static inline 想定):
- `core/box/tiny_unified_lifo_box.h`
API:
- `unified_cache_try_pop_lifo(int class_idx) -> void* base_or_null`
- `unified_cache_try_push_lifo(int class_idx, void* base) -> int handled(1/0)`
実装方針:
- `TinyUnifiedCache``tail` を “top” とみなす(互換優先)
- LIFO enabled のときは head は使わない(または 0 に固定)
### Patch 3: 統合点(入口で 1 回だけ)
統合候補(優先順):
1) `core/box/tiny_front_hot_box.h`hot alloc/free の実体)
2) `core/front/tiny_unified_cache.h`(広範囲に効かせたい場合)
原則:
- “mode 判定” は **関数入口で 1 回だけ**
- hot パス中で mode の再判定を散らさないPhase 11 の反省)
### Patch 4: 可視化(最小)
必要なときだけ:
- LIFO hit/miss を TLS カウンタatomic 禁止)
- ワンショット dumpENV opt-in
---
## 3. A/B同一バイナリ
Baseline:
```sh
HAKMEM_TINY_UNIFIED_LIFO=0 scripts/run_mixed_10_cleanenv.sh
```
Optimized:
```sh
HAKMEM_TINY_UNIFIED_LIFO=1 scripts/run_mixed_10_cleanenv.sh
```
追加(局所性が効くか):
```sh
HAKMEM_BENCH_C7_ONLY=1 HAKMEM_TINY_UNIFIED_LIFO=0 scripts/run_mixed_10_cleanenv.sh
HAKMEM_BENCH_C7_ONLY=1 HAKMEM_TINY_UNIFIED_LIFO=1 scripts/run_mixed_10_cleanenv.sh
```
---
## 4. 健康診断
```sh
scripts/verify_health_profiles.sh
```
---
## 5. Rollback
- `export HAKMEM_TINY_UNIFIED_LIFO=0`

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@ -98,13 +98,18 @@ hakmem.o: core/hakmem.c core/hakmem.h core/hakmem_build_flags.h \
core/box/../front/../box/ptr_type_box.h \
core/box/../front/../box/tiny_front_config_box.h \
core/box/../front/../box/../hakmem_build_flags.h \
core/box/../front/../box/tiny_tcache_box.h \
core/box/../front/../box/../hakmem_tiny_config.h \
core/box/../front/../box/../tiny_nextptr.h \
core/box/../front/../box/tiny_tcache_env_box.h \
core/box/../front/../tiny_region_id.h core/box/../front/../hakmem_tiny.h \
core/box/../front/../box/tiny_env_box.h \
core/box/../front/../box/tiny_front_hot_box.h \
core/box/../front/../box/../hakmem_tiny_config.h \
core/box/../front/../box/../tiny_region_id.h \
core/box/../front/../box/../front/tiny_unified_cache.h \
core/box/../front/../box/tiny_header_box.h \
core/box/../front/../box/tiny_unified_lifo_box.h \
core/box/../front/../box/tiny_unified_lifo_env_box.h \
core/box/../front/../box/tiny_front_cold_box.h \
core/box/../front/../box/tiny_layout_box.h \
core/box/../front/../box/tiny_hotheap_v2_box.h \
@ -346,14 +351,19 @@ core/box/../front/tiny_unified_cache.h:
core/box/../front/../box/ptr_type_box.h:
core/box/../front/../box/tiny_front_config_box.h:
core/box/../front/../box/../hakmem_build_flags.h:
core/box/../front/../box/tiny_tcache_box.h:
core/box/../front/../box/../hakmem_tiny_config.h:
core/box/../front/../box/../tiny_nextptr.h:
core/box/../front/../box/tiny_tcache_env_box.h:
core/box/../front/../tiny_region_id.h:
core/box/../front/../hakmem_tiny.h:
core/box/../front/../box/tiny_env_box.h:
core/box/../front/../box/tiny_front_hot_box.h:
core/box/../front/../box/../hakmem_tiny_config.h:
core/box/../front/../box/../tiny_region_id.h:
core/box/../front/../box/../front/tiny_unified_cache.h:
core/box/../front/../box/tiny_header_box.h:
core/box/../front/../box/tiny_unified_lifo_box.h:
core/box/../front/../box/tiny_unified_lifo_env_box.h:
core/box/../front/../box/tiny_front_cold_box.h:
core/box/../front/../box/tiny_layout_box.h:
core/box/../front/../box/tiny_hotheap_v2_box.h: