3daf75e57f
Fix critical 19x free() slowdown in Mid MT allocator (1KB-8KB range). Root Cause: - Mid MT registers chunks in MidGlobalRegistry - Free path searches Pool's mid_desc registry (different registry!) - Result: 100% lookup failure → 4x cascading lookups → libc fallback Solution (Box Pattern): - Created core/box/mid_free_route_box.h - Try Mid MT registry BEFORE classify_ptr() in free() - Direct route to mid_mt_free() if found - Fall through to existing path if not found Performance Results (bench_mid_mt_gap, 1KB-8KB allocs): - Before: 1.49 M ops/s (19x slower than system malloc) - After: 41.0 M ops/s (+28.9x improvement) - vs System malloc: 1.53x faster (41.0 vs 26.8 M ops/s) Files: - core/box/mid_free_route_box.h (NEW) - Mid Free Route Box - core/box/hak_wrappers.inc.h - Add mid_free_route_try() call - core/hakmem_mid_mt.h - Fix mid_get_min_size() (1024 not 2048) - bench_mid_mt_gap.c (NEW) - Targeted 1KB-8KB benchmark - Makefile - Add bench_mid_mt_gap targets Box Pattern: ✅ Single responsibility, clear contract, testable, minimal change 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
105 lines
3.1 KiB
C
105 lines
3.1 KiB
C
/**
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* mid_free_route_box.h
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*
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* Box: Mid Free Route Box
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* Responsibility: Route Mid MT allocations to correct free path
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* Contract: Try Mid MT registry lookup, return success/failure
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*
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* Part of Phase 5-Step2 fix for 19x free() slowdown
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*
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* Problem:
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* - Mid MT allocator registers chunks in MidGlobalRegistry
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* - Free path searches Pool's mid_desc registry (different registry!)
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* - Result: 100% lookup failure → 4x cascading lookups → 19x slower
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*
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* Solution:
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* - Add Mid MT registry lookup BEFORE Pool registry lookup
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* - Route directly to mid_mt_free() if found
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* - Fall through to existing path if not found
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*
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* Performance Impact:
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* - Before: 1.42 M ops/s (19x slower than system malloc)
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* - After: 14-21 M ops/s (Option B quick fix, 10-15x improvement)
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*
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* Created: 2025-11-29 (Phase 5-Step2 Mid MT Gap Fix)
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*/
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#ifndef MID_FREE_ROUTE_BOX_H
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#define MID_FREE_ROUTE_BOX_H
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#include "../hakmem_mid_mt.h"
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#include <stdbool.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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// ============================================================================
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// Box Contract: Mid MT Free Routing
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// ============================================================================
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/**
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* mid_free_route_try - Try Mid MT free path first
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*
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* @param ptr Pointer to free
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* @return true if handled by Mid MT, false to fall through
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*
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* Box Responsibilities:
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* 1. Query Mid MT registry (mid_registry_lookup)
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* 2. If found: Call mid_mt_free() and return true
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* 3. If not found: Return false (let existing path handle it)
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*
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* Box Guarantees:
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* - Zero side effects if returning false
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* - Correct free if returning true
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* - Thread-safe (Mid MT registry has mutex protection)
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*
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* Performance:
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* - Mid MT hit: O(log N) registry lookup + O(1) free = ~50 cycles
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* - Mid MT miss: O(log N) registry lookup only = ~50 cycles
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* - Compare to current broken path: 4 lookups + libc = ~750 cycles
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*
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* Usage Example:
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* void free(void* ptr) {
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* if (mid_free_route_try(ptr)) return; // Mid MT handled
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* // Fall through to existing free path...
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* }
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*/
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__attribute__((always_inline))
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static inline bool mid_free_route_try(void* ptr) {
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if (!ptr) return false; // NULL ptr, not Mid MT
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// Query Mid MT registry (binary search + mutex)
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size_t block_size = 0;
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int class_idx = 0;
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if (mid_registry_lookup(ptr, &block_size, &class_idx)) {
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// Found in Mid MT registry, route to mid_mt_free()
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mid_mt_free(ptr, block_size);
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return true; // Handled
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}
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// Not in Mid MT registry, fall through to existing path
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return false;
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}
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// ============================================================================
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// Box Observability (Debug/Profiling)
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// ============================================================================
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#if MID_DEBUG
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/**
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* mid_free_route_stats - Print Mid Free Route Box statistics
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*
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* Only available in debug builds (MID_DEBUG=1)
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* Tracks hit/miss rates for performance analysis
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*/
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void mid_free_route_stats(void);
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif // MID_FREE_ROUTE_BOX_H
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