e9b97e9d8e
Phase 74-1 (ENV-gated LOCALIZE): - Result: +0.50% (NEUTRAL) - Runtime branch overhead caused instructions/branches to increase - Diagnosed: Branch tax dominates intended optimization Phase 74-2 (compile-time LOCALIZE): - Result: -0.87% (NEUTRAL, P1 frozen) - Removed runtime branch → instructions -0.6%, branches -2.3% ✓ - But cache-misses +86% (register pressure/spill) → net loss - Conclusion: LOCALIZE本体 works, but fragile to cache effects Key finding: - Dependency chain reduction (LOCALIZE) has low ROI due to cache-miss sensitivity - P1 (LOCALIZE) frozen at default OFF - Next: Phase 74-3 (P0: FASTAPI) - move branches outside hot loop Files: - core/hakmem_build_flags.h: HAKMEM_TINY_UC_LOCALIZE_COMPILED flag - core/box/tiny_unified_cache_hitpath_env_box.h: ENV gate (frozen) - core/front/tiny_unified_cache.h: compile-time #if blocks - docs/analysis/PHASE74_*: Design, instructions, results - CURRENT_TASK.md: P1 frozen, P0 next instructions Also includes: - Phase 69 refill tuning results (archived docs) - PERFORMANCE_TARGETS_SCORECARD.md: Phase 69 baseline update - PHASE70_REFILL_OBSERVABILITY_PREREQS_SSOT.md: Route banner docs 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
198 lines
6.6 KiB
Markdown
198 lines
6.6 KiB
Markdown
# Phase 69-1: Refill Tuning Parameter Sweeps - Results
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**Date**: 2025-12-17
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**Baseline**: Phase 68 PGO (`bench_random_mixed_hakmem_minimal_pgo`)
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**Benchmark**: `scripts/run_mixed_10_cleanenv.sh` (RUNS=10)
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**Goal**: Find +3-6% optimization for M2 milestone (55% of mimalloc)
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---
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## Executive Summary
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**Winner Identified**: **Warm Pool Size=16** achieves **+3.26% (Strong GO)** with ENV-only change.
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- **No code changes required** - Deploy via `HAKMEM_WARM_POOL_SIZE=16` environment variable
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- **Exceeds M2 threshold** (+3.0% Strong GO criterion)
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- **Single strongest improvement** among all tested parameters
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- **Combined optimizations are non-additive** - Warm Pool Size=16 alone outperforms combinations
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⚠️ **Important correction (2025-12 audit)**:
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The previously reported “Refill Batch Size sweep” based on `TINY_REFILL_BATCH_SIZE` was **not measuring a real knob**.
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That macro currently has **zero call sites** (it is defined but not referenced in the active Tiny front path), so any
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observed deltas were **layout/drift noise**, not an algorithmic effect.
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---
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## Full Sweep Results
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### Baseline (Phase 68 PGO)
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| Metric | Value |
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|--------|-------|
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| **Mean** | 60.65M ops/s |
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| **Median** | 60.68M ops/s |
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| **CV** | 1.68% |
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| **% of mimalloc** | 50.93% |
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**Runs**: 10
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**Binary**: `bench_random_mixed_hakmem_minimal_pgo` (PGO optimized)
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---
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### 1. Warm Pool Size Sweep (ENV-only, no recompile)
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**Parameter**: `HAKMEM_WARM_POOL_SIZE` (default: 12 SuperSlabs/class)
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| Size | Mean (M ops/s) | Median (M ops/s) | CV | vs Baseline | Decision |
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|------|----------------|------------------|----|-----------:|----------|
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| **16** | **62.63** | **63.38** | 2.43% | **+3.26%** | **Strong GO** ✓✓✓ |
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| 24 | 62.37 | 62.35 | 1.99% | +2.84% | GO ✓ |
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**Winner**: **Size=16 (+3.26%)**
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**Analysis**:
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- Size=16 exceeds +3.0% Strong GO threshold
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- Size=24 shows diminishing returns (+2.84% vs +3.26%)
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- Optimal sweet spot at Size=16 balances cache hit rate vs memory overhead
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**Command Used**:
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```bash
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# Size=16
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HAKMEM_WARM_POOL_SIZE=16 RUNS=10 BENCH_BIN=./bench_random_mixed_hakmem_minimal_pgo scripts/run_mixed_10_cleanenv.sh
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# Size=24
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HAKMEM_WARM_POOL_SIZE=24 RUNS=10 BENCH_BIN=./bench_random_mixed_hakmem_minimal_pgo scripts/run_mixed_10_cleanenv.sh
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```
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---
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### 2. Unified Cache C5-C7 Sweep (ENV-only, no recompile)
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**Parameter**: `HAKMEM_TINY_UNIFIED_C5`, `HAKMEM_TINY_UNIFIED_C6`, `HAKMEM_TINY_UNIFIED_C7` (default: 128 slots)
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| Cache Size | Mean (M ops/s) | Median (M ops/s) | CV | vs Baseline | Decision |
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|------------|----------------|------------------|----|-----------:|----------|
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| **256** | **61.92** | **61.70** | 1.49% | **+2.09%** | **GO** ✓ |
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| 512 | 61.80 | 62.00 | 1.21% | +1.89% | GO ✓ |
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**Winner**: **Cache=256 (+2.09%)**
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**Analysis**:
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- Cache=256 shows +2.09% improvement (GO threshold)
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- Cache=512 shows diminishing returns (+1.89% vs +2.09%)
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- Larger caches provide marginal gains while increasing memory overhead
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- Lower CV (1.49%) indicates stable performance
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**Command Used**:
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```bash
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# Cache=256
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HAKMEM_TINY_UNIFIED_C5=256 HAKMEM_TINY_UNIFIED_C6=256 HAKMEM_TINY_UNIFIED_C7=256 RUNS=10 BENCH_BIN=./bench_random_mixed_hakmem_minimal_pgo scripts/run_mixed_10_cleanenv.sh
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# Cache=512
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HAKMEM_TINY_UNIFIED_C5=512 HAKMEM_TINY_UNIFIED_C6=512 HAKMEM_TINY_UNIFIED_C7=512 RUNS=10 BENCH_BIN=./bench_random_mixed_hakmem_minimal_pgo scripts/run_mixed_10_cleanenv.sh
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```
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---
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### 3. Combined Optimization Check
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**Configuration**: Warm Pool Size=16 + Unified Cache C5-C7=256
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| Mean (M ops/s) | Median (M ops/s) | CV | vs Baseline | Decision |
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|----------------|------------------|----|-----------:|----------|
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| 62.35 | 62.32 | 1.91% | +2.81% | GO (non-additive) |
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**Analysis**:
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- Combined result (+2.81%) is **LESS than** Warm Pool Size=16 alone (+3.26%)
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- **Non-additive behavior** indicates parameters are not orthogonal
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- **Likely explanation**: Warm pool optimization reduces unified cache miss rate, making cache capacity increase redundant
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- **Recommendation**: Use Warm Pool Size=16 alone for maximum benefit
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**Command Used**:
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```bash
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HAKMEM_WARM_POOL_SIZE=16 HAKMEM_TINY_UNIFIED_C5=256 HAKMEM_TINY_UNIFIED_C6=256 HAKMEM_TINY_UNIFIED_C7=256 RUNS=10 BENCH_BIN=./bench_random_mixed_hakmem_minimal_pgo scripts/run_mixed_10_cleanenv.sh
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```
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---
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### 4. Refill Batch Size Sweep (invalid — macro not wired)
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The `TINY_REFILL_BATCH_SIZE` macro is currently **define-only**:
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```bash
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rg -n "TINY_REFILL_BATCH_SIZE" core
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# -> core/hakmem_tiny_config.h only
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```
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So we do **not** treat it as a tuning parameter until it is actually connected to refill logic.
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If we want to tune refill frequency, use the real knobs:
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- `HAKMEM_TINY_REFILL_COUNT_HOT`
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- `HAKMEM_TINY_REFILL_COUNT_MID`
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- `HAKMEM_TINY_REFILL_COUNT` / `HAKMEM_TINY_REFILL_COUNT_C{0..7}`
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---
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## Recommendations
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### Phase 69-2 (Baseline Promotion)
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**Primary Recommendation**: **Deploy Warm Pool Size=16 (ENV-only)**
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**Rationale**:
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1. **Strongest single improvement** (+3.26%, Strong GO)
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2. **No code changes required** - Zero risk of layout tax
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3. **Immediate deployment** via environment variable
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4. **Exceeds M2 threshold** (+3.0% Strong GO criterion)
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**Deployment**:
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```bash
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# Add to PGO training environment and benchmark scripts
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export HAKMEM_WARM_POOL_SIZE=16
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```
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---
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### Secondary Options (for Phase 69-3+)
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**Option A: Warm Pool Size=16 + Refill Batch=32**
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- **Combined potential**: Unknown (requires testing, may be non-additive like unified cache)
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- **Complexity**: Requires PGO rebuild for Batch=32
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- **Risk**: Layout tax from code change
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**Option B: Warm Pool Size=16 alone (recommended)**
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- **Gain**: +3.26% guaranteed
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- **Complexity**: ENV-only, zero code changes
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- **Risk**: None (reversible via ENV)
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---
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## Raw Data Files
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All 10-run logs saved to:
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- `/tmp/phase69_baseline.log` - Phase 68 PGO baseline
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- `/tmp/phase69_warm16.log` - Warm Pool Size=16
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- `/tmp/phase69_warm24.log` - Warm Pool Size=24
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- `/tmp/phase69_cache256.log` - Unified Cache C5-C7=256
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- `/tmp/phase69_cache512.log` - Unified Cache C5-C7=512
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- `/tmp/phase69_combined.log` - Combined (Warm=16 + Cache=256)
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- `/tmp/phase69_batch32.log` - Refill Batch=32
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---
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## Next Steps
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**Awaiting User Instructions for Phase 69-2**:
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1. Confirm Warm Pool Size=16 as baseline promotion candidate
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2. Decide whether to:
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- Update ENV defaults in `hakmem_tiny_config.h` (preferred for SSOT)
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- Document as recommended ENV setting in README/docs
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- Add to PGO training scripts
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3. Re-run `make pgo-fast-full` with `HAKMEM_WARM_POOL_SIZE=16` in training environment
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4. Update `PERFORMANCE_TARGETS_SCORECARD.md` with new baseline (projected: 62.63M ops/s, ~52.6% of mimalloc)
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---
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**Phase 69-1 Status**: ✅ **COMPLETE**
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**Winner**: **Warm Pool Size=16 (+3.26%, Strong GO, ENV-only)**
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