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Phase 9-2: Remove Legacy Backend & Unify to Shared Pool (50M ops/s)

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- Removed Legacy Backend fallback; Shared Pool is now the sole backend.
- Removed Soft Cap limit in Shared Pool to allow full memory management.
- Implemented EMPTY slab recycling with batched meta->used decrement in remote drain.
- Updated tiny_free_local_box to return is_empty status for safe recycling.
- Fixed race condition in release path by removing from legacy list early.
- Achieved 50.3M ops/s in WS8192 benchmark (+200% vs baseline).
This commit is contained in:
Moe Charm (CI)
2025-12-01 13:47:23 +09:00
parent 3a040a545a
commit 0bc33dc4f5
7 changed files with 92 additions and 102 deletions
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44
core/hakmem_shared_pool_release.c
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@ -26,6 +26,23 @@ shared_pool_release_slab(SuperSlab* ss, int slab_idx)
return;
}
// Phase 9-2 FIX: Promote Legacy SuperSlabs to Shared Pool on first recycle
// If we are recycling a slot from a Legacy SS, we must remove it from the
// Legacy list (g_superslab_heads) to prevent Legacy Backend from allocating
// from it simultaneously (Double Allocation Race).
// This effectively transfers ownership to Shared Pool.
extern void remove_superslab_from_legacy_head(SuperSlab* ss);
remove_superslab_from_legacy_head(ss);
// BUGFIX: Re-check used count after removal. Legacy Backend might have
// allocated from this slab while we were waiting for the lock in remove().
TinySlabMeta* slab_meta = &ss->slabs[slab_idx];
if (atomic_load_explicit(&slab_meta->used, memory_order_acquire) != 0) {
// Legacy Backend stole this slab. It's now an orphan (removed from list).
// We abort recycling. It will be recycled when Legacy frees it later.
return;
}
// Debug logging
#if !HAKMEM_BUILD_RELEASE
static int dbg = -1;
@ -46,9 +63,9 @@ shared_pool_release_slab(SuperSlab* ss, int slab_idx)
pthread_mutex_lock(&g_shared_pool.alloc_lock);
TinySlabMeta* slab_meta = &ss->slabs[slab_idx];
// TinySlabMeta* slab_meta = &ss->slabs[slab_idx]; // Already declared above
if (slab_meta->used != 0) {
// Not actually empty; nothing to do
// Not actually empty (double check under lock)
if (g_lock_stats_enabled == 1) {
atomic_fetch_add(&g_lock_release_count, 1);
}
@ -160,15 +177,28 @@ shared_pool_release_slab(SuperSlab* ss, int slab_idx)
pthread_mutex_unlock(&g_shared_pool.alloc_lock);
// Remove from legacy backend list (if present) to prevent dangling pointers
extern void remove_superslab_from_legacy_head(SuperSlab* ss);
remove_superslab_from_legacy_head(ss);
// Remove from legacy backend list (moved to top of function)
// extern void remove_superslab_from_legacy_head(SuperSlab* ss);
// remove_superslab_from_legacy_head(ss);
// Free SuperSlab:
// 1. Try LRU cache (hak_ss_lru_push) - lazy deallocation
// 2. Or munmap if LRU is full - eager deallocation
extern void superslab_free(SuperSlab* ss);
superslab_free(ss);
// BUGFIX: Double check total_active_blocks. Legacy Backend might have
// allocated from ANOTHER slab in this SS just before we removed it.
// If so, we must NOT free the SS.
if (atomic_load(&ss->total_active_blocks) == 0) {
extern void superslab_free(SuperSlab* ss);
superslab_free(ss);
} else {
#if !HAKMEM_BUILD_RELEASE
if (dbg == 1) {
fprintf(stderr, "[SP_SLOT_RELEASE] SKIP free ss=%p: total_active_blocks=%u > 0\n",
(void*)ss, atomic_load(&ss->total_active_blocks));
}
#endif
}
return;
}