04186341c1
Implemented Hot/Cold Path separation using Box pattern for Tiny allocations: Performance Improvement (without PGO): - Baseline (Phase 26-A): 53.3 M ops/s - Hot/Cold Box (Phase 4-Step2): 57.2 M ops/s - Gain: +7.3% (+3.9 M ops/s) Implementation: 1. core/box/tiny_front_hot_box.h - Ultra-fast hot path (1 branch) - Removed range check (caller guarantees valid class_idx) - Inline cache hit path with branch prediction hints - Debug metrics with zero overhead in Release builds 2. core/box/tiny_front_cold_box.h - Slow cold path (noinline, cold) - Refill logic (batch allocation from SuperSlab) - Drain logic (batch free to SuperSlab) - Error reporting and diagnostics 3. core/front/malloc_tiny_fast.h - Updated to use Hot/Cold Boxes - Hot path: tiny_hot_alloc_fast() (1 branch: cache empty check) - Cold path: tiny_cold_refill_and_alloc() (noinline, cold attribute) - Clear separation improves i-cache locality Branch Analysis: - Baseline: 4-5 branches in hot path (range check + cache check + refill logic mixed) - Hot/Cold Box: 1 branch in hot path (cache empty check only) - Reduction: 3-4 branches eliminated from hot path Design Principles (Box Pattern): ✅ Single Responsibility: Hot path = cache hit only, Cold path = refill/errors ✅ Clear Contract: Hot returns NULL on miss, Cold handles miss ✅ Observable: Debug metrics (TINY_HOT_METRICS_*) gated by NDEBUG ✅ Safe: Branch prediction hints (TINY_HOT_LIKELY/UNLIKELY) ✅ Testable: Isolated hot/cold paths, easy A/B testing PGO Status: - Temporarily disabled (build issues with __gcov_merge_time_profile) - Will re-enable PGO in future commit after resolving gcc/lto issues - Current benchmarks are without PGO (fair A/B comparison) Other Changes: - .gitignore: Added *.d files (dependency files, auto-generated) - Makefile: PGO targets temporarily disabled (show informational message) - build_pgo.sh: Temporarily disabled (show "PGO paused" message) Next: Phase 4-Step3 (Front Config Box, target +5-8%) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
11 lines
422 B
Bash
Executable File
11 lines
422 B
Bash
Executable File
#!/bin/bash
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#!/bin/bash
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# build_pgo.sh - PGO temporarily disabled
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# NOTE: Phase 4 Tiny front refactor is in progress.
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# PGO/build flow is parked to avoid extra complexity.
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echo "build_pgo.sh: PGO build is temporarily disabled (Phase 4 tiny-front refactor in progress)."
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echo " - Normal build: ./build.sh release bench_random_mixed_hakmem"
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echo " - Tiny benches: ./build.sh release bench_tiny_hot_hakmem"
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exit 1
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