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Phase 23 Unified Cache + PageFaultTelemetry generalization: Mid/VM page-fault bottleneck identified
Summary:
- Phase 23 Unified Cache: +30% improvement (Random Mixed 256B: 18.18M → 23.68M ops/s)
- PageFaultTelemetry: Extended to generic buckets (C0-C7, MID, L25, SSM)
- Measurement-driven decision: Mid/VM page-faults (80-100K) >> Tiny (6K) → prioritize Mid/VM optimization
Phase 23 Changes:
1. Unified Cache implementation (core/front/tiny_unified_cache.{c,h})
- Direct SuperSlab carve (TLS SLL bypass)
- Self-contained pop-or-refill pattern
- ENV: HAKMEM_TINY_UNIFIED_CACHE=1, HAKMEM_TINY_UNIFIED_C{0-7}=128
2. Fast path pruning (tiny_alloc_fast.inc.h, tiny_free_fast_v2.inc.h)
- Unified ON → direct cache access (skip all intermediate layers)
- Alloc: unified_cache_pop_or_refill() → immediate fail to slow
- Free: unified_cache_push() → fallback to SLL only if full
PageFaultTelemetry Changes:
3. Generic bucket architecture (core/box/pagefault_telemetry_box.{c,h})
- PF_BUCKET_{C0-C7, MID, L25, SSM} for domain-specific measurement
- Integration: hak_pool_try_alloc(), l25_alloc_new_run(), shared_pool_allocate_superslab_unlocked()
4. Measurement results (Random Mixed 500K / 256B):
- Tiny C2-C7: 2-33 pages, high reuse (64-3.8 touches/page)
- SSM: 512 pages (initialization footprint)
- MID/L25: 0 (unused in this workload)
- Mid/Large VM benchmarks: 80-100K page-faults (13-16x higher than Tiny)
Ring Cache Enhancements:
5. Hot Ring Cache (core/front/tiny_ring_cache.{c,h})
- ENV: HAKMEM_TINY_HOT_RING_ENABLE=1, HAKMEM_TINY_HOT_RING_C{0-7}=size
- Conditional compilation cleanup
Documentation:
6. Analysis reports
- RANDOM_MIXED_BOTTLENECK_ANALYSIS.md: Page-fault breakdown
- RANDOM_MIXED_SUMMARY.md: Phase 23 summary
- RING_CACHE_ACTIVATION_GUIDE.md: Ring cache usage
- CURRENT_TASK.md: Updated with Phase 23 results and Phase 24 plan
Next Steps (Phase 24):
- Target: Mid/VM PageArena/HotSpanBox (page-fault reduction 80-100K → 30-40K)
- Tiny SSM optimization deferred (low ROI, ~6K page-faults already optimal)
- Expected improvement: +30-50% for Mid/Large workloads
Generated with Claude Code
Co-Authored-By: Claude <noreply@anthropic.com>
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2025-11-17 02:47:58 +09:00 |
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