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.
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Moe Charm (CI)
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PHASE8_QUICK_REFERENCE.md
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PHASE8_QUICK_REFERENCE.md
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# Phase 8 Benchmark - Quick Reference Card
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## TL;DR - The Numbers
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```
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Working Set 256 (Hot Cache):
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HAKMEM: 79.2 M ops/s
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System: 86.7 M ops/s (1.09x faster)
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mimalloc: 114.9 M ops/s (1.45x faster)
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Working Set 8192 (Realistic):
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HAKMEM: 16.5 M ops/s ⚠️ CRITICAL
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System: 57.1 M ops/s (3.46x faster) ⚠️ CRITICAL
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mimalloc: 96.5 M ops/s (5.85x faster) ⚠️ CRITICAL
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Scalability (WS256 → WS8192):
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HAKMEM: 4.80x degradation 🔴 BROKEN
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System: 1.52x degradation ✅ Good
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mimalloc: 1.19x degradation ✅ Excellent
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```
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## Critical Issues Found
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### 1. SuperSlab Scaling Failure (SEVERITY: CRITICAL)
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- **Impact**: 246% slower than System malloc at WS8192
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- **Evidence**: "shared_fail→legacy" logs show slab exhaustion
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- **Root cause**: SuperSlab architecture doesn't scale beyond hot cache
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### 2. Fast Path Overhead (SEVERITY: MEDIUM)
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- **Impact**: 9.4% slower than System malloc at WS256
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- **Evidence**: Even with everything in cache, HAKMEM lags
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- **Root cause**: TLS drain overhead, SuperSlab lookup costs
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### 3. Fragmentation Issues (SEVERITY: HIGH)
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- **Impact**: 4.8x performance degradation vs 1.5x for System
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- **Evidence**: Linear performance collapse with working set size
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- **Root cause**: SuperSlab list becomes inefficient
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## Phase 9 Priorities
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### Week 1: Investigation
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1. Profile SuperSlab lookup latency
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2. Measure cache/TLB miss rates
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3. Analyze "shared_fail→legacy" root cause
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4. Measure fragmentation at different working set sizes
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### Week 2: Targeted Fixes
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1. Implement hash table for SuperSlab lookup
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2. Experiment with 1MB/2MB SuperSlab sizes
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3. Fix shared slab capacity issues
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4. Optimize fast path (inline more, reduce branches)
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## Success Criteria
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### Minimum (Required)
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- WS256: 79.2 → 85 M ops/s (+7%)
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- WS8192: 16.5 → 35 M ops/s (+112%)
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- Degradation: 4.80x → 2.50x or better
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### Stretch Goal
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- WS256: 90+ M ops/s (match System malloc)
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- WS8192: 45+ M ops/s (80% of System malloc)
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- Degradation: 2.00x or better
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## If Phase 9 Fails (<30 M ops/s at WS8192)
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Switch to **Hybrid Architecture**:
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- Keep: TLS fast path layer
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- Replace: SuperSlab backend → jemalloc-style arenas
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- Timeline: +3 weeks
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- Success probability: 75%
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## Benchmark Reproducibility
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All benchmarks available at:
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- `/mnt/workdisk/public_share/hakmem/phase8_comprehensive_benchmark_results.txt` (raw data)
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- `./bench_random_mixed_hakmem 10000000 8192` (reproduce HAKMEM)
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- `./bench_random_mixed_system 10000000 8192` (reproduce System)
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- `./bench_random_mixed_mi 10000000 8192` (reproduce mimalloc)
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5 runs per benchmark, StdDev < 2.5% (statistically robust).
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## Reports Generated
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1. **PHASE8_COMPREHENSIVE_BENCHMARK_REPORT.md** - Full statistical analysis
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2. **PHASE8_TECHNICAL_ANALYSIS.md** - Deep dive into root causes
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3. **PHASE8_VISUAL_SUMMARY.md** - Visual charts and decision matrix
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4. **PHASE8_QUICK_REFERENCE.md** - This file (quick lookup)
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## Next Steps
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1. Read PHASE8_VISUAL_SUMMARY.md for decision matrix
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2. Read PHASE8_TECHNICAL_ANALYSIS.md for root cause details
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3. Begin Phase 9 investigation (Week 1)
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4. Re-evaluate after 2 weeks
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---
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**Date**: 2025-11-30
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**Status**: Phase 8 COMPLETE, Phase 9 READY
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**Critical Path**: Fix SuperSlab scaling or switch to Hybrid architecture
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