Files
hakmem/docs/analysis/PHASE6_3_FIX_SUMMARY.md
Moe Charm (CI) a9ddb52ad4 ENV cleanup: Remove BG/HotMag vars & guard fprintf (Larson 52.3M ops/s)
Phase 1 完了:環境変数整理 + fprintf デバッグガード

ENV変数削除(BG/HotMag系):
- core/hakmem_tiny_init.inc: HotMag ENV 削除 (~131 lines)
- core/hakmem_tiny_bg_spill.c: BG spill ENV 削除
- core/tiny_refill.h: BG remote 固定値化
- core/hakmem_tiny_slow.inc: BG refs 削除

fprintf Debug Guards (#if !HAKMEM_BUILD_RELEASE):
- core/hakmem_shared_pool.c: Lock stats (~18 fprintf)
- core/page_arena.c: Init/Shutdown/Stats (~27 fprintf)
- core/hakmem.c: SIGSEGV init message

ドキュメント整理:
- 328 markdown files 削除(旧レポート・重複docs)

性能確認:
- Larson: 52.35M ops/s (前回52.8M、安定動作)
- ENV整理による機能影響なし
- Debug出力は一部残存(次phase で対応)

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>
2025-11-26 14:45:26 +09:00

2.9 KiB

Phase 6-3 Fast Path: Quick Fix Summary

Root Cause (TL;DR)

Fast Path implementation creates a double-layered allocation path that ALWAYS fails due to SuperSlab OOM:

Fast Path → tiny_fast_refill() → hak_tiny_alloc_slow() → OOM (NULL)
  ↓
Fallback → Box Refactor path → ALSO OOM → crash

Result: -20% regression (4.19M → 3.35M ops/s) + 45 GB memory leak


3 Fix Options (Ranked)

Fix #1: Disable Fast Path (IMMEDIATE)

Time: 1 minute Confidence: 100% Target: 4.19M ops/s (restore baseline)

make clean
make BOX_REFACTOR_DEFAULT=1 TINY_FAST_PATH_DEFAULT=0 larson_hakmem
./larson_hakmem 10 8 128 1024 1 12345 4

Why this works: Reverts to proven Box Refactor path (Phase 6-2.2)


Fix #2: Integrate Fast Path with Box Refactor (2-4 hours)

Confidence: 80% Target: 5.0-6.0M ops/s (20-40% improvement)

Change 1: Make tiny_fast_refill() use Box Refactor backend

// File: core/tiny_fastcache.c:tiny_fast_refill()
void* tiny_fast_refill(int class_idx) {
    // OLD: void* ptr = hak_tiny_alloc_slow(size, class_idx);  // OOM!
    // NEW: Use proven Box Refactor path
    void* ptr = hak_tiny_alloc(size);  // ← This works!

    // Rest of refill logic stays the same...
}

Change 2: Remove Fast Path from hak_alloc_at() (avoid double-layer)

// File: core/hakmem.c:hak_alloc_at()
// Comment out lines 682-697 (Fast Path check)
// Keep ONLY in malloc() wrapper (lines 1294-1309)

Why this works:

  • Box Refactor path is proven (4.19M ops/s)
  • Fast Path gets actual cache refills
  • Subsequent allocations hit 3-4 instruction fast path
  • No OOM because Box Refactor handles allocation correctly

Fix #3: Fix SuperSlab OOM (1-2 weeks)

Confidence: 60% Effort: High (deep architectural change)

Only needed if Fix #2 still has OOM issues. See full analysis for details.


  1. Now: Run Fix #1 (restore baseline)
  2. Today: Implement Fix #2 (integrate with Box Refactor)
  3. Test: A/B compare Fix #1 vs Fix #2
  4. Decision:
    • If Fix #2 > 4.5M ops/s → Ship it!
    • If Fix #2 still has OOM → Need Fix #3 (long-term)

Expected Outcomes

Fix Time Score Status
#1 (Disable) 1 min 4.19M ops/s Safe baseline
#2 (Integrate) 2-4 hrs 5.0-6.0M ops/s 🎯 Target
#3 (Root cause) 1-2 weeks Unknown ⚠️ High risk

Why Statistics Don't Show

HAKMEM_TINY_FAST_STATS=1 produces no output because:

  1. No shutdown hook - tiny_fast_print_stats() never called
  2. Thread-local counters - Lost when threads exit
  3. Early crash - OOM kills benchmark before stats printed

Fix: Add to hak_flush_tiny_exit() in hakmem.c:

// Line ~206
extern void tiny_fast_print_stats(void);
tiny_fast_print_stats();

Full analysis: PHASE6_3_REGRESSION_ULTRATHINK.md