6859d589ea
## Major Changes
### 1. Box 3: Pointer Conversion Module (NEW)
- File: core/box/ptr_conversion_box.h
- Purpose: Unified BASE ↔ USER pointer conversion (single source of truth)
- API: PTR_BASE_TO_USER(), PTR_USER_TO_BASE()
- Features: Zero-overhead inline, debug mode, NULL-safe, class 7 headerless support
- Design: Header-only, fully modular, no external dependencies
### 2. POOL_TLS_PHASE1 Default OFF (CRITICAL FIX)
- File: build.sh
- Change: POOL_TLS_PHASE1 now defaults to 0 (was hardcoded to 1)
- Impact: Eliminates pthread_mutex overhead on every free() (was causing 3.3x slowdown)
- Usage: Set POOL_TLS_PHASE1=1 env var to enable if needed
### 3. Pointer Conversion Fixes (PARTIAL)
- Files: core/box/front_gate_box.c, core/tiny_alloc_fast.inc.h, etc.
- Status: Partial implementation using Box 3 API
- Note: Work in progress, some conversions still need review
### 4. Performance Investigation Report (NEW)
- File: HOTPATH_PERFORMANCE_INVESTIGATION.md
- Findings:
- Hotpath works (+24% vs baseline) after POOL_TLS fix
- Still 9.2x slower than system malloc due to:
* Heavy initialization (23.85% of cycles)
* Syscall overhead (2,382 syscalls per 100K ops)
* Workload mismatch (C7 1KB is 49.8%, but only C5 256B has hotpath)
* 9.4x more instructions than system malloc
### 5. Known Issues
- SEGV at 20K-30K iterations (pre-existing bug, not related to pointer conversions)
- Root cause: Likely active counter corruption or TLS-SLL chain issues
- Status: Under investigation
## Performance Results (100K iterations, 256B)
- Baseline (Hotpath OFF): 7.22M ops/s
- Hotpath ON: 8.98M ops/s (+24% improvement ✓)
- System malloc: 82.2M ops/s (still 9.2x faster)
## Next Steps
- P0: Fix 20K-30K SEGV bug (GDB investigation needed)
- P1: Lazy initialization (+20-25% expected)
- P1: C7 (1KB) hotpath (+30-40% expected, biggest win)
- P2: Reduce syscalls (+15-20% expected)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
81 lines
2.8 KiB
C
81 lines
2.8 KiB
C
// front_gate_box.c - Front Gate Box (SFC/SLL priority and helpers)
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#include "front_gate_box.h"
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#include "tiny_alloc_fast_sfc.inc.h"
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#include "tls_sll_box.h" // Box TLS-SLL API
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#include "ptr_conversion_box.h" // Box 3: Pointer conversions
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// TLS SLL state (extern from hakmem_tiny.c)
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extern __thread void* g_tls_sll_head[TINY_NUM_CLASSES];
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extern __thread uint32_t g_tls_sll_count[TINY_NUM_CLASSES];
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extern int g_tls_sll_enable; // set at init via HAKMEM_TINY_TLS_SLL
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// Front breakdown counters (extern from hakmem_tiny.c)
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extern unsigned long long g_front_sfc_hit[];
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extern unsigned long long g_front_sll_hit[];
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// SFC feature flag (extern from hakmem_tiny_sfc.c)
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extern int g_sfc_enabled;
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int front_gate_try_pop(int class_idx, void** out_ptr) {
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if (!out_ptr) return 0;
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// Layer 0: SFC
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if (__builtin_expect(g_sfc_enabled, 1)) {
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void* base = sfc_alloc(class_idx);
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if (base != NULL) {
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g_front_sfc_hit[class_idx]++;
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/* BOX_BOUNDARY: Box 1 (SFC) → Box 3 → Box 4 (User) */
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/* sfc_alloc returns BASE, must convert to USER for caller */
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*out_ptr = PTR_BASE_TO_USER(base, class_idx);
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return 1;
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}
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}
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// Layer 1: TLS SLL
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if (__builtin_expect(g_tls_sll_enable, 1)) {
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void* base = NULL;
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if (tls_sll_pop(class_idx, &base)) {
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g_front_sll_hit[class_idx]++;
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/* BOX_BOUNDARY: Box 1 (TLS SLL) → Box 3 → Box 4 (User) */
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/* tls_sll_pop returns BASE, must convert to USER for caller */
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*out_ptr = PTR_BASE_TO_USER(base, class_idx);
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return 1;
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}
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}
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return 0;
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}
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// Cascade some of refilled blocks into SFC (one-way, safe)
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void front_gate_after_refill(int class_idx, int refilled_count) {
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if (!g_sfc_enabled || refilled_count <= 0) return;
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int to_move = refilled_count / 2;
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if (to_move <= 0) return;
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while (to_move-- > 0 && g_tls_sll_count[class_idx] > 0) {
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// SLL pop
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void* ptr = NULL;
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if (!tls_sll_pop(class_idx, &ptr)) break;
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// SFC push (capacity-guarded inside sfc_free_push)
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if (!sfc_free_push(class_idx, ptr)) {
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// If SFC refused (full), stop early to avoid spinning
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break;
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}
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}
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}
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void front_gate_push_tls(int class_idx, void* ptr) {
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// IMPORTANT: ptr is ALREADY a BASE pointer (callers from tiny_free_fast.inc.h
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// convert USER→BASE before calling tiny_alloc_fast_push)
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// Do NOT double-convert! Pass directly to TLS SLL which expects BASE.
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// Use Box TLS-SLL API (C7-safe; expects base pointer)
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if (!tls_sll_push(class_idx, ptr, UINT32_MAX)) {
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// C7 rejected or capacity exceeded - should not happen in front gate
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// but handle gracefully (silent discard)
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return;
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}
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}
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