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72b38bc994bc771f4e1c8e0f64324c998e0094e2
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Author SHA1 Message Date
Moe Charm (CI)
72b38bc994 Phase E3-FINAL: Fix Box API offset bugs - ALL classes now use correct offsets 
## 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
Moe Charm (CI)
6859d589ea Add Box 3 (Pointer Conversion Layer) and fix POOL_TLS_PHASE1 default 
## Major Changes

### 1. Box 3: Pointer Conversion Module (NEW)
- File: core/box/ptr_conversion_box.h
- Purpose: Unified BASE ↔ USER pointer conversion (single source of truth)
- API: PTR_BASE_TO_USER(), PTR_USER_TO_BASE()
- Features: Zero-overhead inline, debug mode, NULL-safe, class 7 headerless support
- Design: Header-only, fully modular, no external dependencies

### 2. POOL_TLS_PHASE1 Default OFF (CRITICAL FIX)
- File: build.sh
- Change: POOL_TLS_PHASE1 now defaults to 0 (was hardcoded to 1)
- Impact: Eliminates pthread_mutex overhead on every free() (was causing 3.3x slowdown)
- Usage: Set POOL_TLS_PHASE1=1 env var to enable if needed

### 3. Pointer Conversion Fixes (PARTIAL)
- Files: core/box/front_gate_box.c, core/tiny_alloc_fast.inc.h, etc.
- Status: Partial implementation using Box 3 API
- Note: Work in progress, some conversions still need review

### 4. Performance Investigation Report (NEW)
- File: HOTPATH_PERFORMANCE_INVESTIGATION.md
- Findings:
  - Hotpath works (+24% vs baseline) after POOL_TLS fix
  - Still 9.2x slower than system malloc due to:
    * Heavy initialization (23.85% of cycles)
    * Syscall overhead (2,382 syscalls per 100K ops)
    * Workload mismatch (C7 1KB is 49.8%, but only C5 256B has hotpath)
    * 9.4x more instructions than system malloc

### 5. Known Issues
- SEGV at 20K-30K iterations (pre-existing bug, not related to pointer conversions)
- Root cause: Likely active counter corruption or TLS-SLL chain issues
- Status: Under investigation

## Performance Results (100K iterations, 256B)
- Baseline (Hotpath OFF): 7.22M ops/s
- Hotpath ON: 8.98M ops/s (+24% improvement ✓)
- System malloc: 82.2M ops/s (still 9.2x faster)

## Next Steps
- P0: Fix 20K-30K SEGV bug (GDB investigation needed)
- P1: Lazy initialization (+20-25% expected)
- P1: C7 (1KB) hotpath (+30-40% expected, biggest win)
- P2: Reduce syscalls (+15-20% expected)

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

Co-Authored-By: Claude <noreply@anthropic.com>
 2025-11-12 01:01:23 +09:00
HakmemBot
5b31629650 tiny: fix TLS list next_off scope; default TLS_LIST=1; add sentinel guards; header-aware TLS ops; release quiet for benches 2025-11-11 10:00:36 +09:00
Moe Charm (CI)
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
Moe Charm (CI)
52386401b3 Debug Counters Implementation - Clean History 
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