|
|
c9053a43ac
|
Phase 6-2.3~6-2.5: Critical bug fixes + SuperSlab optimization (WIP)
## Phase 6-2.3: Fix 4T Larson crash (active counter bug) ✅
**Problem:** 4T Larson crashed with "free(): invalid pointer", OOM errors
**Root cause:** core/hakmem_tiny_refill_p0.inc.h:103
- P0 batch refill moved freelist blocks to TLS cache
- Active counter NOT incremented → double-decrement on free
- Counter underflows → SuperSlab appears full → OOM → crash
**Fix:** Added ss_active_add(tls->ss, from_freelist);
**Result:** 4T stable at 838K ops/s ✅
## Phase 6-2.4: Fix SEGV in random_mixed/mid_large_mt benchmarks ✅
**Problem:** bench_random_mixed_hakmem, bench_mid_large_mt_hakmem → immediate SEGV
**Root cause #1:** core/box/hak_free_api.inc.h:92-95
- "Guess loop" dereferenced unmapped memory when registry lookup failed
**Root cause #2:** core/box/hak_free_api.inc.h:115
- Header magic check dereferenced unmapped memory
**Fix:**
1. Removed dangerous guess loop (lines 92-95)
2. Added hak_is_memory_readable() check before dereferencing header
(core/hakmem_internal.h:277-294 - uses mincore() syscall)
**Result:**
- random_mixed (2KB): SEGV → 2.22M ops/s ✅
- random_mixed (4KB): SEGV → 2.58M ops/s ✅
- Larson 4T: no regression (838K ops/s) ✅
## Phase 6-2.5: Performance investigation + SuperSlab fix (WIP) ⚠️
**Problem:** Severe performance gaps (19-26x slower than system malloc)
**Investigation:** Task agent identified root cause
- hak_is_memory_readable() syscall overhead (100-300 cycles per free)
- ALL frees hit unmapped_header_fallback path
- SuperSlab lookup NEVER called
- Why? g_use_superslab = 0 (disabled by diet mode)
**Root cause:** core/hakmem_tiny_init.inc:104-105
- Diet mode (default ON) disables SuperSlab
- SuperSlab defaults to 1 (hakmem_config.c:334)
- BUT diet mode overrides it to 0 during init
**Fix:** Separate SuperSlab from diet mode
- SuperSlab: Performance-critical (fast alloc/free)
- Diet mode: Memory efficiency (magazine capacity limits only)
- Both are independent features, should not interfere
**Status:** ⚠️ INCOMPLETE - New SEGV discovered after fix
- SuperSlab lookup now works (confirmed via debug output)
- But benchmark crashes (Exit 139) after ~20 lookups
- Needs further investigation
**Files modified:**
- core/hakmem_tiny_init.inc:99-109 - Removed diet mode override
- PERFORMANCE_INVESTIGATION_REPORT.md - Task agent analysis (303x instruction gap)
**Next steps:**
- Investigate new SEGV (likely SuperSlab free path bug)
- OR: Revert Phase 6-2.5 changes if blocking progress
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
|
2025-11-07 20:31:01 +09:00 |
|
