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Phase 24-26: Hot path atomic telemetry prune (+2.00% cumulative)

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Summary:
- Phase 24 (alloc stats): +0.93% GO
- Phase 25 (free stats): +1.07% GO
- Phase 26 (diagnostics): -0.33% NEUTRAL (code cleanliness)
- Total: 11 atomics compiled-out, +2.00% improvement

Phase 24: OBSERVE tax prune (tiny_class_stats_box.h)
- Added HAKMEM_TINY_CLASS_STATS_COMPILED (default: 0)
- Wrapped 5 stats functions: uc_miss, warm_hit, shared_lock, tls_carve_*
- Result: +0.93% (baseline 56.675M vs compiled-in 56.151M ops/s)

Phase 25: Tiny free stats prune (tiny_superslab_free.inc.h)
- Added HAKMEM_TINY_FREE_STATS_COMPILED (default: 0)
- Wrapped g_free_ss_enter atomic in free hot path
- Result: +1.07% (baseline 57.017M vs compiled-in 56.415M ops/s)

Phase 26: Hot path diagnostic atomics prune
- Added 5 compile gates for low-frequency error counters:
  - HAKMEM_TINY_C7_FREE_COUNT_COMPILED
  - HAKMEM_TINY_HDR_MISMATCH_LOG_COMPILED
  - HAKMEM_TINY_HDR_META_MISMATCH_COMPILED
  - HAKMEM_TINY_METRIC_BAD_CLASS_COMPILED
  - HAKMEM_TINY_HDR_META_FAST_COMPILED
- Result: -0.33% NEUTRAL (within noise, kept for cleanliness)

Alignment with mimalloc principles:
- "No atomics on hot path" - telemetry moved to compile-time opt-in
- Fixed per-op tax elimination
- Production builds: maximum performance (atomics compiled-out)
- Research builds: full diagnostics (COMPILED=1)

Generated with Claude Code
https://claude.com/claude-code

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
This commit is contained in:
Moe Charm (CI)
2025-12-16 05:35:11 +09:00
parent 4d9429e14c
commit 8052e8b320
32 changed files with 4979 additions and 2204 deletions
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22
core/box/tiny_front_hot_box.h
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@ -108,15 +108,17 @@
//
__attribute__((always_inline))
static inline void* tiny_hot_alloc_fast(int class_idx) {
// Phase 15 v1: Mode check at entry (once per call, not scattered in hot path)
int lifo_mode = tiny_unified_lifo_enabled();
extern __thread TinyUnifiedCache g_unified_cache[];
// TLS cache access (1 cache miss)
// NOTE: Range check removed - caller (hak_tiny_size_to_class) guarantees valid class_idx
TinyUnifiedCache* cache = &g_unified_cache[class_idx];
#if HAKMEM_TINY_UNIFIED_LIFO_COMPILED
// Phase 15 v1: Mode check at entry (once per call, not scattered in hot path)
// Phase 22: Compile-out when disabled (default OFF)
int lifo_mode = tiny_unified_lifo_enabled();
// Phase 15 v1: LIFO vs FIFO mode switch
if (lifo_mode) {
// === LIFO MODE: Stack-based (LIFO) ===
@ -134,8 +136,9 @@ static inline void* tiny_hot_alloc_fast(int class_idx) {
TINY_HOT_METRICS_MISS(class_idx);
return NULL;
}
#endif
// === FIFO MODE: Ring-based (existing) ===
// === FIFO MODE: Ring-based (existing, default) ===
// Branch 1: Cache empty check (LIKELY hit)
// Hot path: cache has objects (head != tail)
// Cold path: cache empty (head == tail) → refill needed
@ -187,15 +190,17 @@ static inline void* tiny_hot_alloc_fast(int class_idx) {
//
__attribute__((always_inline))
static inline int tiny_hot_free_fast(int class_idx, void* base) {
// Phase 15 v1: Mode check at entry (once per call, not scattered in hot path)
int lifo_mode = tiny_unified_lifo_enabled();
extern __thread TinyUnifiedCache g_unified_cache[];
// TLS cache access (1 cache miss)
// NOTE: Range check removed - caller guarantees valid class_idx
TinyUnifiedCache* cache = &g_unified_cache[class_idx];
#if HAKMEM_TINY_UNIFIED_LIFO_COMPILED
// Phase 15 v1: Mode check at entry (once per call, not scattered in hot path)
// Phase 22: Compile-out when disabled (default OFF)
int lifo_mode = tiny_unified_lifo_enabled();
// Phase 15 v1: LIFO vs FIFO mode switch
if (lifo_mode) {
// === LIFO MODE: Stack-based (LIFO) ===
@ -214,8 +219,9 @@ static inline int tiny_hot_free_fast(int class_idx, void* base) {
#endif
return 0; // FULL
}
#endif
// === FIFO MODE: Ring-based (existing) ===
// === FIFO MODE: Ring-based (existing, default) ===
// Calculate next tail (for full check)
uint16_t next_tail = (cache->tail + 1) & cache->mask;