hakmem/docs/STATUS_2025_12_03_CURRENT.md

Project Status - 2025-12-03

Last Updated: 2025-12-03 (Current) Status: 🔴 CRITICAL BLOCKER - TLS SLL Header Corruption Detected Overall Phase: Phase 1 Implementation + Phase 2 Design (Blocked)

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Summary

The hakmem memory allocator project has reached a critical stability issue during Phase 1 performance benchmarking. The baseline configuration crashes with a TLS SLL header corruption error that affects all configurations, indicating a shared code path problem rather than a Phase 1 specific issue.

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Completed Phases ✅

Phase 0: Type Safety & Box Architecture Framework

• ✅ Phantom Types implementation (ptr_type_box.h)
• ✅ Pointer conversion API (ptr_conversion_box.h)
• ✅ Root cause analysis verified (Gemini's mathematical proof)
• ✅ Box theory framework established
• ✅ Include order dependencies resolved (commit 2dc9d5d59)
• ✅ Magazine Spill pointer wrapping fixed (commit f3f75ba3d)

Phase 1: Logic Centralization & Optimization (TLS Hint Box)

• ✅ Designed TLS SuperSlab Hint Box (tls_ss_hint_box.h)
• ✅ Implemented 5-function API (init, lookup, update, clear, stats)
• ✅ Integrated into free path (lines 477-481, 550-555)
• ✅ Integrated into alloc path (lines 115-122, 179-186)
• ✅ Created 6 unit tests - ALL PASSING
• ✅ Compiled as header-only (zero overhead when disabled)
• ⚠️ Performance benchmarking: Only 2.3% improvement vs target 15-20%

Phase 2: Headerless Mode Design

• ✅ Comprehensive design document (21KB)
• ✅ All 7 task specifications documented
• ✅ A/B toggle flag designed (HAKMEM_TINY_HEADERLESS)
• ✅ SuperSlab Registry integration planned
• ✅ TLS SLL validation skipping documented
• ❌ BLOCKED: Cannot proceed - baseline instability

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Current Critical Issue 🔴

Symptom

[TLS_SLL_HDR_RESET] cls=1 base=0x7ef296abf8c8 got=0x31 expect=0xa1 count=0
Segmentation fault (core dumped)

Location

• File: core/box/tls_sll_box.h
• Lines: 282-303
• Function: tls_sll_pop_impl()
• Operation: Header validation during free path

Impact

• ❌ TC1 (Baseline) crashes after ~22 seconds of execution
• ❌ Cannot validate Phase 1 performance improvements
• ❌ Cannot proceed to Phase 2 implementation
• ❌ Cannot benchmark any configuration variant

Root Cause

Unknown - One of six documented patterns:

1. RAW pointer vs BASE pointer type mismatch
2. Header offset mismatch (write vs read location)
3. Atomic fence missing (compiler/CPU reordering)
4. Adjacent block overflow corrupting header
5. Class index mismatch during push/pop
6. Headerless mode interference

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Documents Created for Diagnosis

Three comprehensive documents have been created to guide the fix:

1. docs/CHATGPT_CONTEXT_SUMMARY.md

   • Quick facts about the problem
   • Architecture overview
   • File locations and data structures
   • Timeline estimate: 4-8 hours

2. docs/CHATGPT_HANDOFF_TLS_DIAGNOSIS.md

   • Step-by-step 7-step task breakdown
   • Detailed instructions for each phase
   • Expected validation criteria
   • Success metrics

3. docs/TLS_SLL_HEADER_CORRUPTION_DIAGNOSIS.md (Existing, 1,150+ lines)

   • Deep dive into all 6 root cause patterns
   • Code examples for each pattern
   • Minimal test case template
   • Diagnostic logging instrumentation
   • Fix code templates
   • 7-step validation procedure

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What Needs to Happen

Immediate (Blocking)

1. [CHATGPT TASK] Diagnose TLS SLL header corruption
   • Use the three diagnostic documents
   • Follow 7-step process
   • Expected delivery: 4-8 hours
   • Success criterion: TC1 baseline completes without crashes

After Diagnosis

2. [DEPENDS ON #1] Validate Phase 1 performance

   • Run full benchmarks (TC1, TC2, TC3)
   • Confirm TLS Hint Box improves performance
   • Identify optimization opportunities

3. [DEPENDS ON #1] Proceed to Phase 2

   • Implement Headerless mode (ON/OFF toggle)
   • Validate alignment guarantees
   • Benchmark performance trade-offs

4. [DEPENDS ON #1-3] Phase 102 Planning

   • Design MemApi bridge
   • Connect hakmem to nyrt Ring0 runtime

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Recent Git History

ad852e5d5 - Priority-2 ENV Cache: hakmem_batch.c (1変数追加、1箇所置換)
b741d61b4 - Priority-2 ENV Cache: hakmem_debug.c (1変数追加、1箇所置換)
22a67e5ca - Priority-2 ENV Cache: hakmem_smallmid.c (1変数追加、1箇所置換)
f0e77a000 - Priority-2 ENV Cache: hakmem_tiny.c (3箇所置換)
183b10673 - Priority-2 ENV Cache: Shared Pool Release (1箇所置換)

[Earlier commits in THIS session:]
94f9ea51  - Implement TLS SuperSlab Hint Box (Phase 1) ✅
           - Header-only implementation (256 lines)
           - 5 function APIs
           - 6 unit tests - ALL PASSING
           - Benchmarked at only 2.3% improvement

f3f75ba3d - Fix Magazine Spill RAW pointer type conversion ✅
           - Added HAK_BASE_FROM_RAW() wrapping
           - hakmem_tiny_refill.inc.h:228
           - Verified with cfrac/sh8bench

2dc9d5d59 - Fix include order in hakmem.c ✅
           - Moved hak_kpi_util.inc.h before hak_core_init.inc.h
           - Resolved undefined reference errors
           - Clean build verified

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File Statistics

Category	Count	Status
Core Implementation	47 files	✅ Compiles
Box Components	15 files	✅ Box theory applied
Test Suite	23 tests	⚠️ 6 TLS Hint tests PASS, 17 others untested due to crash
Documentation	12 documents	✅ Comprehensive
Build Artifacts	libhakmem.so	✅ Generates (547 KB)

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Build Status

$ make clean && make shared -j8
✅ Compilation: SUCCESS
✅ Linking: SUCCESS
✅ Output: ./libhakmem.so (547 KB)
✅ Debug symbols: Included (-g flag)

$ LD_PRELOAD=./libhakmem.so ./mimalloc-bench/out/bench/sh8bench
❌ Execution: SEGFAULT
Error: [TLS_SLL_HDR_RESET] cls=1 base=0x... got=0x31 expect=0xa1
Exit Code: 139 (SIGSEGV)
Runtime: ~22 seconds before crash

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Key Metrics

Metric	Value	Status
Compilation Time	8-12 sec	✅ Good
Executable Size	547 KB	✅ Reasonable
Baseline Performance	N/A	❌ Crashes
Phase 1 Optimization	2.3%	⚠️ Below target (15-20%)
Code Coverage	Unknown	⏳ Pending baseline fix

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Next Steps (Clearly Defined)

For ChatGPT (Immediate Handoff)

Task: Diagnose and fix TLS SLL header corruption

Documents to Use:

1. docs/CHATGPT_CONTEXT_SUMMARY.md - Quick reference
2. docs/CHATGPT_HANDOFF_TLS_DIAGNOSIS.md - Step-by-step instructions
3. docs/TLS_SLL_HEADER_CORRUPTION_DIAGNOSIS.md - Deep reference

Steps:

1. Read diagnostic documents
2. Create minimal reproducer
3. Add diagnostic logging
4. Run diagnostic test
5. Identify root cause pattern
6. Implement surgical fix (1-5 lines)
7. Validate with TC1 baseline test

Success Criterion:

• ✅ sh8bench runs to completion
• ✅ cfrac runs without errors
• ✅ No TLS_SLL_HDR_RESET errors
• ✅ < 5% performance regression

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Notes for Future Reference

Architecture Decisions Locked In

1. Box Theory: Each component is isolated with clear APIs
2. Phantom Types: Type safety in Debug mode, zero-cost in Release
3. Pointer Conversion: Centralized in ptr_conversion_box.h
4. Layout Definitions: Centralized in tiny_layout_box.h
5. TLS SLL: Thread-local single-linked list with header validation
6. SuperSlab Registry: Maps free pointers to class information (Phase 2)

Known Working Patterns

• Magazine Spill RAW→BASE wrapping (fixed)
• Include order dependencies (fixed)
• Unit test framework (6 TLS Hint tests passing)
• Box header-only compilation (verified)

Known Issues Needing Diagnosis

• TLS SLL header corruption (PRIMARY BLOCKER)
• Phase 1 performance below target (SECONDARY - optimization opportunity)
• Headerless mode not yet validated (DEPENDS ON PRIMARY FIX)

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Handoff Status

✅ All diagnostic documents prepared ✅ Comprehensive step-by-step instructions created ✅ Root cause patterns documented with code examples ✅ Minimal test case template provided ✅ Validation procedures detailed

🎯 Ready for ChatGPT handoff

Next: Pass the three documents to ChatGPT with the directive to follow the 7-step process.

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Questions for Next Phase

After the fix is complete, the following should be investigated:

1. Why is Phase 1 performance only 2.3% improvement vs expected 15-20%?

   • Is 4 slots enough for the cache?
   • Are there secondary bottlenecks?
   • Does perf/cachegrind show cache misses?

2. Can Phase 2 Headerless provide better performance than Phase 1?

   • What are the trade-offs?
   • Is the SuperSlab Registry lookup overhead worth it?

3. How does hakmem compare to mimalloc and jemalloc across different workloads?

   • Are there specific use cases where hakmem excels?
   • Where does it fall short?

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Status: 🔴 CRITICAL - Awaiting ChatGPT diagnosis and fix

Estimated Resolution Time: 4-8 hours from ChatGPT engagement

Next Review: After ChatGPT completes TLS SLL diagnosis and fix