72b38bc994
Phase E3-FINAL: Fix Box API offset bugs - ALL classes now use correct offsets
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## Root Cause Analysis (GPT5)
**Physical Layout Constraints**:
- Class 0: 8B = [1B header][7B payload] → offset 1 = 9B needed = ❌ IMPOSSIBLE
- Class 1-6: >=16B = [1B header][15B+ payload] → offset 1 = ✅ POSSIBLE
- Class 7: 1KB → offset 0 (compatibility)
**Correct Specification**:
- HAKMEM_TINY_HEADER_CLASSIDX != 0:
- Class 0, 7: next at offset 0 (overwrites header when on freelist)
- Class 1-6: next at offset 1 (after header)
- HAKMEM_TINY_HEADER_CLASSIDX == 0:
- All classes: next at offset 0
**Previous Bug**:
- Attempted "ALL classes offset 1" unification
- Class 0 with offset 1 caused immediate SEGV (9B > 8B block size)
- Mixed 2-arg/3-arg API caused confusion
## Fixes Applied
### 1. Restored 3-Argument Box API (core/box/tiny_next_ptr_box.h)
```c
// Correct signatures
void tiny_next_write(int class_idx, void* base, void* next_value)
void* tiny_next_read(int class_idx, const void* base)
// Correct offset calculation
size_t offset = (class_idx == 0 || class_idx == 7) ? 0 : 1;
```
### 2. Updated 123+ Call Sites Across 34 Files
- hakmem_tiny_hot_pop_v4.inc.h (4 locations)
- hakmem_tiny_fastcache.inc.h (3 locations)
- hakmem_tiny_tls_list.h (12 locations)
- superslab_inline.h (5 locations)
- tiny_fastcache.h (3 locations)
- ptr_trace.h (macro definitions)
- tls_sll_box.h (2 locations)
- + 27 additional files
Pattern: `tiny_next_read(base)` → `tiny_next_read(class_idx, base)`
Pattern: `tiny_next_write(base, next)` → `tiny_next_write(class_idx, base, next)`
### 3. Added Sentinel Detection Guards
- tiny_fast_push(): Block nodes with sentinel in ptr or ptr->next
- tls_list_push(): Block nodes with sentinel in ptr or ptr->next
- Defense-in-depth against remote free sentinel leakage
## Verification (GPT5 Report)
**Test Command**: `./out/release/bench_random_mixed_hakmem --iterations=70000`
**Results**:
- ✅ Main loop completed successfully
- ✅ Drain phase completed successfully
- ✅ NO SEGV (previous crash at iteration 66151 is FIXED)
- ℹ️ Final log: "tiny_alloc(1024) failed" is normal fallback to Mid/ACE layers
**Analysis**:
- Class 0 immediate SEGV: ✅ RESOLVED (correct offset 0 now used)
- 66K iteration crash: ✅ RESOLVED (offset consistency fixed)
- Box API conflicts: ✅ RESOLVED (unified 3-arg API)
## Technical Details
### Offset Logic Justification
```
Class 0: 8B block → next pointer (8B) fits ONLY at offset 0
Class 1: 16B block → next pointer (8B) fits at offset 1 (after 1B header)
Class 2: 32B block → next pointer (8B) fits at offset 1
...
Class 6: 512B block → next pointer (8B) fits at offset 1
Class 7: 1024B block → offset 0 for legacy compatibility
```
### Files Modified (Summary)
- Core API: `box/tiny_next_ptr_box.h`
- Hot paths: `hakmem_tiny_hot_pop*.inc.h`, `tiny_fastcache.h`
- TLS layers: `hakmem_tiny_tls_list.h`, `hakmem_tiny_tls_ops.h`
- SuperSlab: `superslab_inline.h`, `tiny_superslab_*.inc.h`
- Refill: `hakmem_tiny_refill.inc.h`, `tiny_refill_opt.h`
- Free paths: `tiny_free_magazine.inc.h`, `tiny_superslab_free.inc.h`
- Documentation: Multiple Phase E3 reports
## Remaining Work
None for Box API offset bugs - all structural issues resolved.
Future enhancements (non-critical):
- Periodic `grep -R '*(void**)' core/` to detect direct pointer access violations
- Enforce Box API usage via static analysis
- Document offset rationale in architecture docs
🤖 Generated with [Claude Code](https://claude.com/claude-code )
Co-Authored-By: Claude <noreply@anthropic.com >
2025-11-13 06:50:20 +09:00
d5302e9c87
Phase 7 follow-up: header-aware in BG spill, TLS drain, and aggressive inline macros
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- bg_spill: link/traverse next at base+1 for C0–C6, base for C7
- lifecycle: drain TLS SLL and fast caches reading next with header-aware offsets
- tiny_alloc_fast_inline: POP/PUSH macros made header-aware to match tls_sll_box rules
- add optional FREE_WRAP_ENTER trace (HAKMEM_FREE_WRAP_TRACE) for early triage
Result: 0xa0/…0099 bogus free logs gone; remaining SIGBUS appears in free path early. Next: instrument early libc fallback or guard invalid pointers during init to pinpoint source.
2025-11-10 18:21:32 +09:00
c9053a43ac
Phase 6-2.3~6-2.5: Critical bug fixes + SuperSlab optimization (WIP)
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## 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
52386401b3
Debug Counters Implementation - Clean History
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Major Features:
- Debug counter infrastructure for Refill Stage tracking
- Free Pipeline counters (ss_local, ss_remote, tls_sll)
- Diagnostic counters for early return analysis
- Unified larson.sh benchmark runner with profiles
- Phase 6-3 regression analysis documentation
Bug Fixes:
- Fix SuperSlab disabled by default (HAKMEM_TINY_USE_SUPERSLAB)
- Fix profile variable naming consistency
- Add .gitignore patterns for large files
Performance:
- Phase 6-3: 4.79 M ops/s (has OOM risk)
- With SuperSlab: 3.13 M ops/s (+19% improvement)
This is a clean repository without large log files.
🤖 Generated with [Claude Code](https://claude.com/claude-code )
Co-Authored-By: Claude <noreply@anthropic.com >
2025-11-05 12:31:14 +09:00
