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hakmem/docs/analysis/ENV_CLEANUP_CANDIDATES.md
Moe Charm (CI) e3e4cab833 Cleanup: Unify type naming and Cold Iface architecture 
Refactoring:
- Type naming: Rename small_page_v4 → SmallPageMeta, small_class_heap_v4 → SmallClassHeap, small_heap_ctx_v4 → SmallHeapCtx
- Keep backward compatibility aliases for existing code
- SmallSegment struct unified, clean forward declarations
- Cold Iface: Remove vtable (SmallColdIfaceV4 struct) in favor of direct function calls
- Simplify refill_page/retire_page to direct calls, not callbacks
- smallobject_hotbox_v4.c: Update to call small_cold_v4_* functions directly

Documentation:
- Add docs/analysis/ENV_CLEANUP_CANDIDATES.md
- Categorize ENVs: KEEP (production), RESEARCH (opt-in), DELETE (obsolete)
- v2 code: Keep as research infrastructure (complete, safe, gated)
- v4 code: Research scaffold for future mid-level allocator

Build:
- ビルド成功（警告のみ）
- Backward compatible, all existing code still works

🤖 Generated with Claude Code

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2025-12-10 23:30:32 +09:00

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ENV Variable Cleanup Candidates

Date: 2025-12-10 Status: Documentation for code cleanup planning

Summary

This document lists environment variables that are candidates for cleanup, categorization, and potential removal. The analysis is based on current usage in bench profiles, default configurations, and implementation status.

Categories

1. KEEP: Core Production (Always ON by default)

These ENVs control essential features that are ON by default in all standard profiles.

ENV Default Purpose Status
HAKMEM_TINY_FRONT_V3_ENABLED 1 Front v3 fast path CORE
HAKMEM_TINY_FRONT_V3_LUT_ENABLED 1 Front v3 lookup table CORE
HAKMEM_SMALL_HEAP_V3_ENABLED 1 SmallObject HotBox v3 CORE
HAKMEM_SMALL_HEAP_V3_CLASSES 0x80 SmallObject v3 class mask (C7 by default) CORE
HAKMEM_TINY_C7_ULTRA_ENABLED 1 C7 ULTRA segment path CORE
HAKMEM_POOL_V1_FLATTEN_ENABLED 0 Pool v1 flatten fast path (OFF default) SAFE

2. RESEARCH: Experimental & Gate-able (OFF by default)

These ENVs control alternative/experimental implementations. All are OFF by default, enabling opt-in for A/B testing.

ENV Default Purpose Status Notes
HAKMEM_SMALL_HEAP_V4_ENABLED 0 SmallObject HotBox v4 (research) RESEARCH Phase v4-mid-0 onwards
HAKMEM_SMALL_HEAP_V4_CLASSES 0x0 SmallObject v4 class mask RESEARCH Opt-in only
HAKMEM_TINY_HOTHEAP_V2 0 TinyHotHeap v2 (research) RESEARCH Complete but disabled
HAKMEM_TINY_HOTHEAP_CLASSES 0x00 TinyHotHeap class mask RESEARCH v2 only, OFF by default
HAKMEM_POOL_V2_ENABLED 0 Pool HotBox v2 (research) RESEARCH Stub, not used
HAKMEM_POOL_V2_CLASSES 0x0 Pool v2 class mask RESEARCH Unused
HAKMEM_SMALL_SEGMENT_V4_ENABLED 0 SmallSegment v4 (research) RESEARCH Phase v4 onwards
HAKMEM_TINY_C7_ULTRA_HEADER_LIGHT 0 C7 ULTRA header optimization (research) RESEARCH Experimental

3. DELETE CANDIDATES: Dead/Obsolete Code

These ENVs should be considered for removal (after confirming no active usage):

ENV Status Reason Action
HAKMEM_TINY_FRONT_V2 OBSOLETE Front v2 replaced by v3 Consider deletion
HAKMEM_TINY_HEAP_V2 RESEARCH-ONLY Magazine variant, no perf gain Keep as research
POOL_V2_* (all) STUB Not fully implemented Consider deletion

4. CONFIGURATION: Profile-specific (Should not be user-editable)

These ENVs are set by bench profiles and should not be manually edited:

ENV Typical Value Purpose
HAKMEM_BENCH_MIN_SIZE 16 or 257 Workload size range (bench only)
HAKMEM_BENCH_MAX_SIZE 1024 or 768 Workload size range (bench only)
HAKMEM_PROFILE MIXED_TINYV3_C7_SAFE Bench profile selection
HAKMEM_TINY_HEAP_PROFILE C7_SAFE Tiny heap profile

5. STATISTICS & DEBUG (Non-functional)

These ENVs control measurement and debugging, not behavior:

ENV Default Purpose
HAKMEM_SMALL_HEAP_V3_STATS 0 SmallObject v3 stats collection
HAKMEM_TINY_HOTHEAP_V2_STATS 0 TinyHotHeap v2 stats collection
HAKMEM_SS_OS_STATS 0 SuperSlab OS stats
HAKMEM_POOL_V1_FLATTEN_STATS 0 Pool flatten stats

Recommended Action Plan

Phase 1: Immediate Documentation (Done)

  • Categorize all active ENVs
  • Document which are production vs. research
  • Mark deletion candidates

Phase 2: Cleanup (Future)

  1. Create ENV_DEFAULTS.h: Consolidate default values
  2. Deprecate dead code: Mark HAKMEM_TINY_FRONT_V2, POOL_V2_* as obsolete
  3. Organize env boxes: Group by category
    • core/box/env/production_env_box.h (KEEP)
    • core/box/env/research_env_box.h (RESEARCH)
    • core/box/env/profile_env_box.h (PROFILE)

Phase 3: Deletion (Later)

  • Confirm zero references to deprecated ENVs
  • Remove associated code (v2, pool_v2)
  • Update documentation

Default Configuration (Current Standard)

The MIXED_TINYV3_C7_SAFE profile (Mixed workload baseline) uses:

HAKMEM_BENCH_MIN_SIZE=16
HAKMEM_BENCH_MAX_SIZE=1024
HAKMEM_TINY_HEAP_PROFILE=C7_SAFE
HAKMEM_TINY_C7_HOT=1
HAKMEM_TINY_HOTHEAP_V2=0              # OFF
HAKMEM_SMALL_HEAP_V3_ENABLED=1        # ON
HAKMEM_SMALL_HEAP_V3_CLASSES=0x80     # C7-only
HAKMEM_SMALL_HEAP_V4_ENABLED=0        # OFF (research)
HAKMEM_POOL_V2_ENABLED=0              # OFF (research)
HAKMEM_TINY_FRONT_V3_ENABLED=1        # ON
HAKMEM_TINY_FRONT_V3_LUT_ENABLED=1    # ON
HAKMEM_TINY_C7_ULTRA_ENABLED=1        # ON

Notes

  • v2 code is complete and safe: Not marked for deletion; remains as research/A/B testing infrastructure.
  • v4 code is scaffolding: Phase v4-mid-0 introduces type skeleton; later phases will add implementation.
  • Research boxes are intentional: Pool v2, TinyHeap v2, and v4 variants serve as design exploration layers.