Files
hakmem/core/box
Moe Charm (CI) c19bb6a3bc Phase 6-B: Header-based Mid MT free (lock-free, +2.65% improvement)
Performance Results (bench_mid_mt_gap, 1KB-8KB, ws=256):
- Before: 41.0 M ops/s (mutex-protected registry)
- After:  42.09 M ops/s (+2.65% improvement)

Expected vs Actual:
- Expected: +17-27% (based on perf showing 13.98% mutex overhead)
- Actual:   +2.65% (needs investigation)

Implementation:
- Added MidMTHeader (8 bytes) to each Mid MT allocation
- Allocation: Write header with block_size, class_idx, magic (0xAB42)
- Free: Read header for O(1) metadata lookup (no mutex!)
- Eliminated entire registry infrastructure (127 lines deleted)

Changes:
- core/hakmem_mid_mt.h: Added MidMTHeader, removed registry structures
- core/hakmem_mid_mt.c: Updated alloc/free, removed registry functions
- core/box/mid_free_route_box.h: Header-based detection instead of registry lookup

Code Quality:
 Lock-free (no pthread_mutex operations)
 Simpler (O(1) header read vs O(log N) binary search)
 Smaller binary (127 lines deleted)
 Positive improvement (no regression)

Next: Investigate why improvement is smaller than expected

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

Co-Authored-By: Claude <noreply@anthropic.com>
2025-11-29 15:45:29 +09:00
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