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hakmem/PHASE8_INDEX.md
Moe Charm (CI) 4ef0171bc0 feat: Add ACE allocation failure tracing and debug hooks 
This commit introduces a comprehensive tracing mechanism for allocation failures within the Adaptive Cache Engine (ACE) component. This feature allows for precise identification of the root cause for Out-Of-Memory (OOM) issues related to ACE allocations.

Key changes include:
- **ACE Tracing Implementation**:
  - Added  environment variable to enable/disable detailed logging of allocation failures.
  - Instrumented , , and  to distinguish between "Threshold" (size class mismatch), "Exhaustion" (pool depletion), and "MapFail" (OS memory allocation failure).
- **Build System Fixes**:
  - Corrected  to ensure  is properly linked into , resolving an  error.
- **LD_PRELOAD Wrapper Adjustments**:
  - Investigated and understood the  wrapper's behavior under , particularly its interaction with  and  checks.
  - Enabled debugging flags for  environment to prevent unintended fallbacks to 's  for non-tiny allocations, allowing comprehensive testing of the  allocator.
- **Debugging & Verification**:
  - Introduced temporary verbose logging to pinpoint execution flow issues within  interception and  routing. These temporary logs have been removed.
  - Created  to facilitate testing of the tracing features.

This feature will significantly aid in diagnosing and resolving allocation-related OOM issues in  by providing clear insights into the failure pathways.
2025-12-01 16:37:59 +09:00

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Phase 8 Comprehensive Benchmark - Report Index

Completion Date: 2025-11-30 Benchmark Status: COMPLETE (30/30 runs successful) Next Phase: Phase 9 - SuperSlab Deep Dive

Quick Navigation

Start Here

Detailed Analysis

Raw Data

Key Findings (30-second read)

Working Set 256 (Hot Cache):
  HAKMEM:    79.2 M ops/s
  System:    86.7 M ops/s  (+9.4% faster)
  mimalloc: 114.9 M ops/s  (+45.2% faster)

Working Set 8192 (Realistic):
  HAKMEM:    16.5 M ops/s  ⚠️ CRITICAL
  System:    57.1 M ops/s  (+246% faster)
  mimalloc:  96.5 M ops/s  (+485% faster)

Scalability:
  HAKMEM degrades 4.80x (WS256 → WS8192)  🔴 BROKEN
  System degrades 1.52x                    ✅ Good
  mimalloc degrades 1.19x                  ✅ Excellent

Critical Issue: SuperSlab architecture does not scale beyond hot cache.

What to Read Based on Your Role

For Project Managers

  1. Read: PHASE8_EXECUTIVE_SUMMARY.md (5 min)
  2. Decision needed: Approve Phase 9 investigation (2 weeks, targeted fixes)
  3. Backup plan: Hybrid Architecture if Phase 9 fails (adds 3 weeks)

For Developers

  1. Read: PHASE8_QUICK_REFERENCE.md (2 min)
  2. Read: PHASE8_VISUAL_SUMMARY.md (5 min)
  3. Prepare for: Phase 9 profiling and optimization work

For Performance Engineers

  1. Read: PHASE8_TECHNICAL_ANALYSIS.md (15 min)
  2. Review: phase8_comprehensive_benchmark_results.txt (raw data)
  3. Focus on: SuperSlab scaling issues, cache/TLB misses

For Architects

  1. Read: PHASE8_TECHNICAL_ANALYSIS.md (15 min)
  2. Read: PHASE8_VISUAL_SUMMARY.md (decision matrix)
  3. Evaluate: Hybrid Architecture option if Phase 9 fails

Reproducibility

All benchmarks can be reproduced:

# HAKMEM Phase 8
./bench_random_mixed_hakmem 10000000 256    # Hot cache
./bench_random_mixed_hakmem 10000000 8192   # Realistic

# System malloc
./bench_random_mixed_system 10000000 256
./bench_random_mixed_system 10000000 8192

# mimalloc
./bench_random_mixed_mi 10000000 256
./bench_random_mixed_mi 10000000 8192

Each benchmark was run 5 times. Standard deviation < 2.5% for all runs.

Report File Sizes

File Size Read Time
PHASE8_EXECUTIVE_SUMMARY.md 7.5K 8 min
PHASE8_QUICK_REFERENCE.md 3.2K 3 min
PHASE8_VISUAL_SUMMARY.md 7.2K 7 min
PHASE8_TECHNICAL_ANALYSIS.md 8.8K 15 min
PHASE8_COMPREHENSIVE_BENCHMARK_REPORT.md 4.9K 5 min
phase8_comprehensive_benchmark_results.txt 11K N/A (raw data)
Total 42.6K 38 min

Critical Actions Required

Immediate (This Week)

  • Review PHASE8_EXECUTIVE_SUMMARY.md
  • Approve Phase 9 investigation budget (2 weeks)
  • Assign developer resources for profiling work

Week 1 (Phase 9 Investigation)

  • Add profiling instrumentation (cache/TLB misses)
  • Analyze "shared_fail→legacy" root cause
  • Measure SuperSlab fragmentation at different working sets
  • Benchmark alternative SuperSlab sizes (1MB, 2MB, 4MB)

Week 2 (Phase 9 Fixes)

  • Implement hash table for SuperSlab lookup
  • Fix shared slab capacity issues
  • Optimize fast path (inline, reduce branches)
  • Re-run benchmarks, evaluate results

Decision Point (End of Week 2)

  • If WS8192 >35 M ops/s: Continue optimization (Phases 10-12)
  • If WS8192 <30 M ops/s: Switch to Hybrid Architecture (Phases 10-14)

Success Metrics

Phase 9 Minimum (Required)

  • WS256: 79.2 → 85+ M ops/s (+7%)
  • WS8192: 16.5 → 35+ M ops/s (+112%)
  • Degradation: 4.80x → 2.50x or better

Phase 12 Target (Production Ready)

  • WS256: 90+ M ops/s (match System malloc)
  • WS8192: 45+ M ops/s (80% of System malloc)
  • Degradation: <2.0x (competitive)

Timeline

Week 0  (Now):        Phase 8 COMPLETE
Week 1-2:             Phase 9 - Investigation + Fixes
Week 3:               Decision Point
Week 4-7 (Best):      Optimization → Production Ready
Week 4-9 (Likely):    Hybrid Architecture → Production Ready
Week 4-12 (Worst):    Complete Rewrite → Production Ready

Questions?

  • Technical questions → See PHASE8_TECHNICAL_ANALYSIS.md
  • Performance questions → See PHASE8_COMPREHENSIVE_BENCHMARK_REPORT.md
  • Strategic questions → See PHASE8_EXECUTIVE_SUMMARY.md
  • Quick answers → See PHASE8_QUICK_REFERENCE.md

Prepared by: Automated Benchmark System Executed on: 2025-11-30 06:04-06:07 JST Location: /mnt/workdisk/public_share/hakmem/ Status: All deliverables complete, Phase 9 ready to begin