Phase v7-5b: C5+C6 multi-class expansion (+4.3% improvement)

- Add C5 (256B blocks) support alongside C6 (512B blocks) - Same segment shared between C5/C6 (page_meta.class_idx distinguishes) - SMALL_V7_CLASS_SUPPORTED() macro for class validation - Extend small_v7_block_size() for C5 (switch statement) A/B Result: C6-only v7 avg 7.64M ops/s → C5+C6 v7 avg 7.97M ops/s (+4.3%) Criteria: C6 protected ✅, C5 net positive ✅, TLS bloat none ✅ ENV: HAKMEM_SMALL_HEAP_V7_CLASSES=0x60 (bit5+bit6) 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2025-12-12 05:11:02 +09:00
parent 17ceed619c
commit d5aa3110c6
5 changed files with 146 additions and 20 deletions
--- a/core/box/smallobject_cold_iface_v7_box.h
+++ b/core/box/smallobject_cold_iface_v7_box.h
@ -102,17 +102,18 @@ typedef struct SmallPageStatsV7 {
 void small_cold_v7_publish_stats(const SmallPageStatsV7* stats);

 // ============================================================================
-// Block Size Lookup (C6-only for v7-2)
+// Block Size Lookup (v7-5b: C5+C6)
 // ============================================================================

 /// Get block size for class index
-/// v7-2: Only C6 (512B) is implemented
+/// v7-5b: C5 (256B) and C6 (512B) supported
 static inline size_t small_v7_block_size(uint32_t class_idx) {
-    // v7-2: C6-only
-    if (class_idx == SMALL_V7_C6_CLASS_IDX) {
-        return SMALL_V7_C6_BLOCK_SIZE;  // 512
+    // v7-5b: C5+C6 multi-class
+    switch (class_idx) {
+        case SMALL_V7_C5_CLASS_IDX: return SMALL_V7_C5_BLOCK_SIZE;  // 256
+        case SMALL_V7_C6_CLASS_IDX: return SMALL_V7_C6_BLOCK_SIZE;  // 512
+        default: return 0;  // Unsupported class
    }
-    return 0;  // Unsupported class
 }

 #endif // HAKMEM_SMALLOBJECT_COLD_IFACE_V7_BOX_H
--- a/core/box/smallobject_hotbox_v7_box.h
+++ b/core/box/smallobject_hotbox_v7_box.h
@ -1,14 +1,18 @@
-// smallobject_hotbox_v7_box.h - SmallObject HotBox v7 (Phase v7-5a: Hot path極限最適化)
+// smallobject_hotbox_v7_box.h - SmallObject HotBox v7 (Phase v7-5b: C5+C6 Multi-class)
 //
 // Role:
 //   - SmallObject v7 fast path for alloc/free
-//   - C6-only implementation (512B blocks, 64KiB pages, 2MiB segments)
+//   - C5+C6 implementation (256B/512B blocks, 64KiB pages, 2MiB segments)
 //   - Uses SmallHeapCtx_v7 + SmallSegment_v7 + ColdIface_v7
 //
 // v7-5a optimizations:
 //   - Stats (alloc_count, free_count, live_current) removed from hot path
 //   - Global atomic stats gated by ENV (HAKMEM_V7_HOT_STATS)
 //   - Header write kept (required due to intrusive freelist overlapping block[0])
+//
+// v7-5b additions:
+//   - C5 support (256B blocks) with minimal TLS overhead
+//   - Same segment shared between C5 and C6 (page_meta.class_idx distinguishes)

 #pragma once

@ -67,7 +71,7 @@ static inline void small_v7_log_class_mismatch(void* ptr, uint8_t hint, uint8_t
 // Alloc Fast Path
 // ============================================================================

-// small_heap_alloc_fast_v7() - v7 alloc (C6-only, v7-5a: Hot path極限最適化)
+// small_heap_alloc_fast_v7() - v7 alloc (v7-5b: C5+C6 multi-class)
 //
 // Flow:
 //   1. Get TLS context
@ -80,9 +84,11 @@ static inline void small_v7_log_class_mismatch(void* ptr, uint8_t hint, uint8_t
 //   - Per-page stats (alloc_count, live_current) removed from hot path
 //   - Global atomic stats gated by ENV (HAKMEM_V7_HOT_STATS)
 //
+// v7-5b: C5+C6 support (same code path, different block sizes)
+//
 static inline void* small_heap_alloc_fast_v7(size_t size, uint8_t class_idx) {
-    // v7-2: Only C6 is implemented
-    if (unlikely(class_idx != SMALL_V7_C6_CLASS_IDX)) {
+    // v7-5b: C5 or C6 supported
+    if (unlikely(!SMALL_V7_CLASS_SUPPORTED(class_idx))) {
        return NULL;  // Unsupported class -> front falls back
    }

@ -152,7 +158,7 @@ static inline void* small_heap_alloc_fast_v7(size_t size, uint8_t class_idx) {
 // Free Fast Path
 // ============================================================================

-// small_heap_free_fast_v7() - v7 free (C6-only, v7-5a: Hot path極限最適化)
+// small_heap_free_fast_v7() - v7 free (v7-5b: C5+C6 multi-class)
 //
 // Flow:
 //   1. TLS segment hint hit (skip RegionIdBox)
@ -162,6 +168,8 @@ static inline void* small_heap_alloc_fast_v7(size_t size, uint8_t class_idx) {
 //   - Stats (free_count, live_current) removed from hot path
 //   - Global atomic stats gated by ENV
 //
+// v7-5b: C5+C6 support (page->class_idx determines actual class)
+//
 // @param ptr: USER pointer to free
 // @param class_idx_hint: Class index hint from front/header (may be ignored)
 // @return: true if handled by v7, false if not v7-managed (front should fallback)
@ -194,8 +202,8 @@ static inline bool small_heap_free_fast_v7(void* ptr, uint8_t class_idx_hint) {

        SmallPageMeta_v7* page = &seg->page_meta[page_idx];

-        // Validate page is in use and C6-only
-        if (unlikely(page->capacity == 0 || page->class_idx != SMALL_V7_C6_CLASS_IDX)) {
+        // v7-5b: Validate page is in use and C5 or C6
+        if (unlikely(page->capacity == 0 || !SMALL_V7_CLASS_SUPPORTED(page->class_idx))) {
            return false;
        }

@ -245,8 +253,8 @@ regionid_fallback:

        SmallPageMeta_v7* page = &seg->page_meta[page_idx];

-        // Validate page is in use and C6-only
-        if (unlikely(page->capacity == 0 || page->class_idx != SMALL_V7_C6_CLASS_IDX)) {
+        // v7-5b: Validate page is in use and C5 or C6
+        if (unlikely(page->capacity == 0 || !SMALL_V7_CLASS_SUPPORTED(page->class_idx))) {
            return false;
        }

--- a/core/box/smallsegment_v7_box.h
+++ b/core/box/smallsegment_v7_box.h
@ -22,12 +22,20 @@
 #define SMALL_SEGMENT_V7_MAGIC      0xC07E57u              // C0(re) v7

 // ============================================================================
-// C6 Class Configuration (v7-2: C6-only)
+// Class Configuration (v7-5b: C5+C6)
 // ============================================================================

+// C6: 513-768B → 512B blocks
 #define SMALL_V7_C6_CLASS_IDX       6
 #define SMALL_V7_C6_BLOCK_SIZE      512

+// C5: 257-512B → 256B blocks (v7-5b)
+#define SMALL_V7_C5_CLASS_IDX       5
+#define SMALL_V7_C5_BLOCK_SIZE      256
+
+// v7-5b: Class support check macro
+#define SMALL_V7_CLASS_SUPPORTED(ci) ((ci) == 5 || (ci) == 6)
+
 // ============================================================================
 // Page Index Calculation
 // ============================================================================
--- a/core/smallobject_cold_iface_v7.c
+++ b/core/smallobject_cold_iface_v7.c
@ -1,12 +1,16 @@
-// smallobject_cold_iface_v7.c - SmallObject ColdIface v7 implementation (Phase v7-5a)
+// smallobject_cold_iface_v7.c - SmallObject ColdIface v7 implementation (Phase v7-5b)
 //
 // Purpose:
 //   - Page refill: acquire page from segment, carve freelist
 //   - Page retire: release empty page back to segment, publish stats
 //
 // v7-5a optimizations:
-//   - Header written at carve time (not on hot path alloc)
+//   - Header written at alloc time (not carve - freelist overlaps block[0])
 //   - Stats collected at retire time (not on hot path)
+//
+// v7-5b additions:
+//   - C5 support (256B blocks) alongside C6 (512B blocks)
+//   - Same segment shared between C5/C6, page_meta.class_idx distinguishes

 #include <stdlib.h>
 #include <string.h>
@ -129,7 +133,7 @@ SmallPageMeta_v7* small_cold_v7_refill_page(SmallHeapCtx_v7* ctx, uint32_t class
        return NULL;
    }

-    // v7-2: Only C6 is supported
+    // v7-5b: C5 (256B) and C6 (512B) supported
    size_t block_size = small_v7_block_size(class_idx);
    if (unlikely(block_size == 0)) {
        return NULL;  // Unsupported class