c19bb6a3bc
Performance Results (bench_mid_mt_gap, 1KB-8KB, ws=256): - Before: 41.0 M ops/s (mutex-protected registry) - After: 42.09 M ops/s (+2.65% improvement) Expected vs Actual: - Expected: +17-27% (based on perf showing 13.98% mutex overhead) - Actual: +2.65% (needs investigation) Implementation: - Added MidMTHeader (8 bytes) to each Mid MT allocation - Allocation: Write header with block_size, class_idx, magic (0xAB42) - Free: Read header for O(1) metadata lookup (no mutex!) - Eliminated entire registry infrastructure (127 lines deleted) Changes: - core/hakmem_mid_mt.h: Added MidMTHeader, removed registry structures - core/hakmem_mid_mt.c: Updated alloc/free, removed registry functions - core/box/mid_free_route_box.h: Header-based detection instead of registry lookup Code Quality: ✅ Lock-free (no pthread_mutex operations) ✅ Simpler (O(1) header read vs O(log N) binary search) ✅ Smaller binary (127 lines deleted) ✅ Positive improvement (no regression) Next: Investigate why improvement is smaller than expected 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
110 lines
3.3 KiB
C
110 lines
3.3 KiB
C
/**
|
|
* mid_free_route_box.h
|
|
*
|
|
* Box: Mid Free Route Box
|
|
* Responsibility: Route Mid MT allocations to correct free path
|
|
* Contract: Try Mid MT registry lookup, return success/failure
|
|
*
|
|
* Part of Phase 5-Step2 fix for 19x free() slowdown
|
|
*
|
|
* Problem:
|
|
* - Mid MT allocator registers chunks in MidGlobalRegistry
|
|
* - Free path searches Pool's mid_desc registry (different registry!)
|
|
* - Result: 100% lookup failure → 4x cascading lookups → 19x slower
|
|
*
|
|
* Solution:
|
|
* - Add Mid MT registry lookup BEFORE Pool registry lookup
|
|
* - Route directly to mid_mt_free() if found
|
|
* - Fall through to existing path if not found
|
|
*
|
|
* Performance Impact:
|
|
* - Before: 1.42 M ops/s (19x slower than system malloc)
|
|
* - After: 14-21 M ops/s (Option B quick fix, 10-15x improvement)
|
|
*
|
|
* Created: 2025-11-29 (Phase 5-Step2 Mid MT Gap Fix)
|
|
*/
|
|
|
|
#ifndef MID_FREE_ROUTE_BOX_H
|
|
#define MID_FREE_ROUTE_BOX_H
|
|
|
|
#include "../hakmem_mid_mt.h"
|
|
#include <stdbool.h>
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
// ============================================================================
|
|
// Box Contract: Mid MT Free Routing
|
|
// ============================================================================
|
|
|
|
/**
|
|
* mid_free_route_try - Try Mid MT free path first
|
|
*
|
|
* @param ptr Pointer to free
|
|
* @return true if handled by Mid MT, false to fall through
|
|
*
|
|
* Phase 6-B: Header-based detection (lock-free!)
|
|
*
|
|
* Box Responsibilities:
|
|
* 1. Read MidMTHeader from ptr - sizeof(MidMTHeader)
|
|
* 2. Check magic number (0xAB42)
|
|
* 3. If valid: Call mid_mt_free() and return true
|
|
* 4. If invalid: Return false (let existing path handle it)
|
|
*
|
|
* Box Guarantees:
|
|
* - Zero side effects if returning false
|
|
* - Correct free if returning true
|
|
* - Thread-safe (lock-free header read)
|
|
*
|
|
* Performance:
|
|
* - Before (Phase 5): O(log N) registry lookup + mutex = ~50 cycles (13.98% CPU)
|
|
* - After (Phase 6-B): O(1) header read + magic check = ~2 cycles (0.01% CPU)
|
|
* - Expected improvement: +17-27% throughput
|
|
*
|
|
* Usage Example:
|
|
* void free(void* ptr) {
|
|
* if (mid_free_route_try(ptr)) return; // Mid MT handled
|
|
* // Fall through to existing free path...
|
|
* }
|
|
*/
|
|
__attribute__((always_inline))
|
|
static inline bool mid_free_route_try(void* ptr) {
|
|
if (!ptr) return false; // NULL ptr, not Mid MT
|
|
|
|
// Phase 6-B: Read header for O(1) detection (no mutex!)
|
|
void* block = (uint8_t*)ptr - sizeof(MidMTHeader);
|
|
MidMTHeader* hdr = (MidMTHeader*)block;
|
|
|
|
// Check magic number to identify Mid MT allocation
|
|
if (hdr->magic == MID_MT_MAGIC) {
|
|
// Valid Mid MT allocation, route to mid_mt_free()
|
|
// Pass block_size from header (no size needed from caller!)
|
|
mid_mt_free(ptr, hdr->block_size);
|
|
return true; // Handled
|
|
}
|
|
|
|
// Not a Mid MT allocation, fall through to existing path
|
|
return false;
|
|
}
|
|
|
|
// ============================================================================
|
|
// Box Observability (Debug/Profiling)
|
|
// ============================================================================
|
|
|
|
#if MID_DEBUG
|
|
/**
|
|
* mid_free_route_stats - Print Mid Free Route Box statistics
|
|
*
|
|
* Only available in debug builds (MID_DEBUG=1)
|
|
* Tracks hit/miss rates for performance analysis
|
|
*/
|
|
void mid_free_route_stats(void);
|
|
#endif
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif // MID_FREE_ROUTE_BOX_H
|