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49969d2e0f
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feat(Phase 1-1): Complete getenv elimination from malloc/free hot paths (+39-42% perf)
## Summary
Eliminated all getenv() calls from malloc/free wrappers and allocator hot paths by implementing
constructor-based environment variable caching. This achieves 39-42% performance improvement
(36s → 22s on sh8bench single-thread).
## Performance Impact
- sh8bench 1 thread: 35-36s → 21-22s (+39-42% improvement) 🚀
- sh8bench 8 threads: ~15s (maintained)
- getenv overhead: 36.32% → 0% (completely eliminated)
## Changes
### New Files
- **core/box/tiny_env_box.{c,h}**: Centralized environment variable cache for Tiny allocator
- Caches 43 environment variables (HAKMEM_TINY_*, HAKMEM_SLL_*, HAKMEM_SS_*, etc.)
- Constructor-based initialization with atomic CAS for thread safety
- Inline accessor tiny_env_cfg() for hot path access
- **core/box/wrapper_env_box.{c,h}**: Environment cache for malloc/free wrappers
- Caches 3 wrapper variables (HAKMEM_STEP_TRACE, HAKMEM_LD_SAFE, HAKMEM_FREE_WRAP_TRACE)
- Constructor priority 101 ensures early initialization
- Replaces all lazy-init patterns in wrapper code
### Modified Files
- **Makefile**: Added tiny_env_box.o and wrapper_env_box.o to OBJS_BASE and SHARED_OBJS
- **core/box/hak_wrappers.inc.h**:
- Removed static lazy-init variables (g_step_trace, ld_safe_mode cache)
- Replaced with wrapper_env_cfg() lookups (wcfg->step_trace, wcfg->ld_safe_mode)
- All getenv() calls eliminated from malloc/free hot paths
- **core/hakmem.c**:
- Added hak_ld_env_init() with constructor for LD_PRELOAD caching
- Added hak_force_libc_ctor() for HAKMEM_FORCE_LIBC_ALLOC* caching
- Simplified hak_ld_env_mode() to return cached value only
- Simplified hak_force_libc_alloc() to use cached values
- Eliminated all getenv/atoi calls from hot paths
## Technical Details
### Constructor Initialization Pattern
All environment variables are now read once at library load time using __attribute__((constructor)):
```c
__attribute__((constructor(101)))
static void wrapper_env_ctor(void) {
wrapper_env_init_once(); // Atomic CAS ensures exactly-once init
}
```
### Thread Safety
- Atomic compare-and-swap (CAS) ensures single initialization
- Spin-wait for initialization completion in multi-threaded scenarios
- Memory barriers (memory_order_acq_rel) ensure visibility
### Hot Path Impact
Before: Every malloc/free → getenv("LD_PRELOAD") + getenv("HAKMEM_STEP_TRACE") + ...
After: Every malloc/free → Single pointer dereference (wcfg->field)
## Next Optimization Target (Phase 1-2)
Perf analysis reveals libc fallback accounts for ~51% of cycles:
- _int_malloc: 15.04%
- malloc: 9.81%
- _int_free: 10.07%
- malloc_consolidate: 9.27%
- unlink_chunk: 6.82%
Reducing libc fallback from 51% → 10% could yield additional +25-30% improvement.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: ChatGPT <chatgpt@openai.com>
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2025-12-02 16:16:51 +09:00 |
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