5685c2f4c9
Problem: Warm pool had 0% hit rate (only 1 hit per 3976 misses) despite being implemented, causing all cache misses to go through expensive superslab_refill registry scans. Root Cause Analysis: - Warm pool was initialized once and pushed a single slab after each refill - When that slab was exhausted, it was discarded (not pushed back) - Next refill would push another single slab, which was immediately exhausted - Pool would oscillate between 0 and 1 items, yielding 0% hit rate Solution: Secondary Prefill on Cache Miss When warm pool becomes empty, we now do multiple superslab_refills and prefill the pool with 3 additional HOT superlslabs before attempting to carve. This builds a working set of slabs that can sustain allocation pressure. Implementation Details: - Modified unified_cache_refill() cold path to detect empty pool - Added prefill loop: when pool count == 0, load 3 extra superlslabs - Store extra slabs in warm pool, keep 1 in TLS for immediate carving - Track prefill events in g_warm_pool_stats[].prefilled counter Results (1M Random Mixed 256B allocations): - Before: C7 hits=1, misses=3976, hit_rate=0.0% - After: C7 hits=3929, misses=3143, hit_rate=55.6% - Throughput: 4.055M ops/s (maintained vs 4.07M baseline) - Stability: Consistent 55.6% hit rate at 5M allocations (4.102M ops/s) Performance Impact: - No regression: throughput remained stable at ~4.1M ops/s - Registry scan avoided in 55.6% of cache misses (significant savings) - Warm pool now functioning as intended with strong locality Configuration: - TINY_WARM_POOL_MAX_PER_CLASS increased from 4 to 16 to support prefill - Prefill budget hardcoded to 3 (tunable via env var if needed later) - All statistics always compiled, ENV-gated printing via HAKMEM_WARM_POOL_STATS=1 Next Steps: - Monitor for further optimization opportunities (prefill budget tuning) - Consider adaptive prefill budget based on class-specific hit rates - Validate at larger allocation counts (10M+ pending registry size fix) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
ACE‑Alloc Paper (Draft)
Files
- main.md — 論文本文のひな形（Markdown）。
- figs/ — 図の置き場（必要に応じて作成）。
Build (optional)
Pandoc がある場合、PDF/HTML などへ変換できます。
# HTML
pandoc -s main.md -o paper.html
# PDF (pandoc + LaTeX 環境が必要)
pandoc -s main.md -o paper.pdf
Repro / Benchmarks
簡易スイープ（性能と RSS）:
scripts/sweep_mem_perf.sh both | tee sweep.csv
代表的なベンチマーク（Tiny / Mixed）:
make bench_tiny_hot_hakmem bench_random_mixed_hakmem
HAKMEM_TINY_PROFILE=full ./bench_tiny_hot_hakmem 64 100 60000
HAKMEM_TINY_PROFILE=conservative ./bench_random_mixed_hakmem 2000000 400 42
環境変数やプロファイルの詳細は docs/specs/ENV_VARS.md を参照してください。