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Phase 5 E5-3: Candidate Analysis (All DEFERRED) + E5-4 Instructions

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E5-3 Analysis Results:
- free_tiny_fast_cold (7.14%): DEFER - cold path, low ROI
- unified_cache_push (3.39%): DEFER - already optimized
- hakmem_env_snapshot_enabled (2.97%): DEFER - low headroom

Key Insight: perf self% is time-weighted, not frequency-weighted.
Cold paths appear hot but have low total impact.

Next: E5-4 (Malloc Tiny Direct Path)
- Apply E5-1 winning pattern to malloc side
- Target: tiny_alloc_gate_fast() gate tax elimination
- ENV gate: HAKMEM_MALLOC_TINY_DIRECT=0/1

Files added:
- docs/analysis/PHASE5_E5_3_ANALYSIS_AND_RECOMMENDATIONS.md
- docs/analysis/PHASE5_E5_4_MALLOC_TINY_DIRECT_NEXT_INSTRUCTIONS.md
- core/box/free_cold_shape_env_box.{h,c} (research box, not tested)
- core/box/free_cold_shape_stats_box.{h,c} (research box, not tested)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Moe Charm (CI)
2025-12-14 06:44:04 +09:00
parent f7b18aaf13
commit 580e7f4fa3
11 changed files with 594 additions and 7 deletions
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27
core/front/malloc_tiny_fast.h
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@ -70,6 +70,8 @@
#include "../box/tiny_metadata_cache_hot_box.h" // Phase 3 C2: Policy hot cache (metadata cache optimization)
#include "../box/tiny_free_route_cache_env_box.h" // Phase 3 D1: Free path route cache
#include "../box/hakmem_env_snapshot_box.h" // Phase 4 E1: ENV snapshot consolidation
#include "../box/free_cold_shape_env_box.h" // Phase 5 E5-3a: Free cold path shape optimization
#include "../box/free_cold_shape_stats_box.h" // Phase 5 E5-3a: Free cold shape stats
// Helper: current thread id (low 32 bits) for owner check
#ifndef TINY_SELF_U32_LOCAL_DEFINED
@ -413,6 +415,28 @@ static int free_tiny_fast_cold(void* ptr, void* base, int class_idx)
}
#endif // !HAKMEM_BUILD_RELEASE
// Phase 5 E5-3a: Optimized cold path shape
// Strategy: Handle common LEGACY path first (use_tiny_heap==0 in Mixed ~90%+)
// Defer expensive LARSON/cross-thread checks to only when heap routing needed
static __thread int g_cold_shape = -1;
if (__builtin_expect(g_cold_shape == -1, 0)) {
g_cold_shape = free_cold_shape_enabled() ? 1 : 0;
}
if (g_cold_shape == 1) {
// Optimized shape: Check use_tiny_heap FIRST
if (__builtin_expect(!use_tiny_heap, 1)) {
// Most common case in Mixed: LEGACY path, no heap routing
// Skip LARSON/cross-thread check entirely (not needed for legacy)
FREE_COLD_SHAPE_STAT_INC(legacy_fast);
FREE_COLD_SHAPE_STAT_INC(enabled_count);
goto legacy_fallback;
}
// Rare: heap routing needed, do full validation
FREE_COLD_SHAPE_STAT_INC(heap_path);
}
// Baseline shape: LARSON check first (current behavior)
// Cross-thread free detection (Larson MT crash fix, ENV gated) + TinyHeap free path
{
static __thread int g_larson_fix = -1;
@ -467,7 +491,7 @@ static int free_tiny_fast_cold(void* ptr, void* base, int class_idx)
}
return 0; // remote push failed; fall back to normal path
}
// Same-thread + TinyHeap route → route-based free
// Same-thread + TinyHeap route → route-based free
if (__builtin_expect(use_tiny_heap, 0)) {
FREE_TINY_FAST_HOTCOLD_STAT_INC(cold_tinyheap);
switch (route) {
@ -541,6 +565,7 @@ static int free_tiny_fast_cold(void* ptr, void* base, int class_idx)
#endif
// Phase REFACTOR-2: Legacy fallback (use unified helper)
legacy_fallback:
FREE_TINY_FAST_HOTCOLD_STAT_INC(cold_legacy_fallback);
tiny_legacy_fallback_free_base(base, class_idx);
return 1;