diff --git a/taichi/runtime/llvm/llvm_runtime_executor.cpp b/taichi/runtime/llvm/llvm_runtime_executor.cpp
index 70e83c0a246e56..551a5bb2ea58f2 100644
--- a/taichi/runtime/llvm/llvm_runtime_executor.cpp
+++ b/taichi/runtime/llvm/llvm_runtime_executor.cpp
@@ -395,6 +395,8 @@ void LlvmRuntimeExecutor::initialize_llvm_runtime_snodes(
   const int root_id = field_cache_data.root_id;
 
   TI_TRACE("Allocating data structure of size {} bytes", root_size);
+  root_size =
+      std::max(root_size, (size_t)taichi_page_size);  // minimal allocation size
   std::size_t rounded_size = taichi::iroundup(root_size, taichi_page_size);
 
   Ptr root_buffer = snode_tree_buffer_manager_->allocate(
diff --git a/taichi/runtime/llvm/snode_tree_buffer_manager.cpp b/taichi/runtime/llvm/snode_tree_buffer_manager.cpp
index 8498ddb736892b..63642ef33ef016 100644
--- a/taichi/runtime/llvm/snode_tree_buffer_manager.cpp
+++ b/taichi/runtime/llvm/snode_tree_buffer_manager.cpp
@@ -9,74 +9,21 @@ SNodeTreeBufferManager::SNodeTreeBufferManager(
   TI_TRACE("SNode tree buffer manager created.");
 }
 
-void SNodeTreeBufferManager::merge_and_insert(Ptr ptr, std::size_t size) {
-  // merge with right block
-  if (ptr_map_[ptr + size]) {
-    std::size_t tmp = ptr_map_[ptr + size];
-    size_set_.erase(std::make_pair(tmp, ptr + size));
-    ptr_map_.erase(ptr + size);
-    size += tmp;
-  }
-  // merge with left block
-  auto map_it = ptr_map_.lower_bound(ptr);
-  if (map_it != ptr_map_.begin()) {
-    auto x = *--map_it;
-    if (x.first + x.second == ptr) {
-      size_set_.erase(std::make_pair(x.second, x.first));
-      ptr_map_.erase(x.first);
-      ptr = x.first;
-      size += x.second;
-    }
-  }
-  size_set_.insert(std::make_pair(size, ptr));
-  ptr_map_[ptr] = size;
-}
-
 Ptr SNodeTreeBufferManager::allocate(JITModule *runtime_jit,
                                      void *runtime,
                                      std::size_t size,
                                      std::size_t alignment,
                                      const int snode_tree_id,
                                      uint64 *result_buffer) {
-  TI_TRACE("allocating memory for SNode Tree {}", snode_tree_id);
-  TI_ASSERT_INFO(snode_tree_id < kMaxNumSnodeTreesLlvm,
-                 "LLVM backend supports up to {} snode trees",
-                 kMaxNumSnodeTreesLlvm);
-  auto set_it = size_set_.lower_bound(std::make_pair(size, nullptr));
-  if (set_it == size_set_.end()) {
-    runtime_jit->call<void *, std::size_t, std::size_t>(
-        "runtime_memory_allocate_aligned", runtime, size, alignment,
-        result_buffer);
-    auto ptr = runtime_exec_->fetch_result<Ptr>(0, result_buffer);
-    roots_[snode_tree_id] = ptr;
-    sizes_[snode_tree_id] = size;
-    return ptr;
-  } else {
-    auto x = *set_it;
-    size_set_.erase(x);
-    ptr_map_.erase(x.second);
-    if (x.first - size > 0) {
-      size_set_.insert(std::make_pair(x.first - size, x.second + size));
-      ptr_map_[x.second + size] = x.first - size;
-    }
-    TI_ASSERT(x.second);
-    roots_[snode_tree_id] = x.second;
-    sizes_[snode_tree_id] = size;
-    return x.second;
-  }
+  auto devalloc = runtime_exec_->allocate_memory_ndarray(size, result_buffer);
+  snode_tree_id_to_device_alloc_[snode_tree_id] = devalloc;
+  return (Ptr)runtime_exec_->get_ndarray_alloc_info_ptr(devalloc);
 }
 
 void SNodeTreeBufferManager::destroy(SNodeTree *snode_tree) {
-  int snode_tree_id = snode_tree->id();
-  TI_TRACE("Destroying SNode tree {}.", snode_tree_id);
-  std::size_t size = sizes_[snode_tree_id];
-  if (size == 0) {
-    TI_DEBUG("SNode tree {} destroy failed.", snode_tree_id);
-    return;
-  }
-  Ptr ptr = roots_[snode_tree_id];
-  merge_and_insert(ptr, size);
-  TI_DEBUG("SNode tree {} destroyed.", snode_tree_id);
+  auto devalloc = snode_tree_id_to_device_alloc_[snode_tree->id()];
+  runtime_exec_->deallocate_memory_ndarray(devalloc);
+  snode_tree_id_to_device_alloc_.erase(snode_tree->id());
 }
 
 }  // namespace taichi::lang
diff --git a/taichi/runtime/llvm/snode_tree_buffer_manager.h b/taichi/runtime/llvm/snode_tree_buffer_manager.h
index fd116ad84d0226..6c1bcb8d291773 100644
--- a/taichi/runtime/llvm/snode_tree_buffer_manager.h
+++ b/taichi/runtime/llvm/snode_tree_buffer_manager.h
@@ -1,6 +1,7 @@
 #pragma once
 #include "taichi/inc/constants.h"
 #include "taichi/struct/snode_tree.h"
+#include "taichi/rhi/public_device.h"
 #define TI_RUNTIME_HOST
 
 #include <set>
@@ -16,8 +17,6 @@ class SNodeTreeBufferManager {
  public:
   explicit SNodeTreeBufferManager(LlvmRuntimeExecutor *runtime_exec);
 
-  void merge_and_insert(Ptr ptr, std::size_t size);
-
   Ptr allocate(JITModule *runtime_jit,
                void *runtime,
                std::size_t size,
@@ -33,6 +32,8 @@ class SNodeTreeBufferManager {
   LlvmRuntimeExecutor *runtime_exec_;
   Ptr roots_[kMaxNumSnodeTreesLlvm];
   std::size_t sizes_[kMaxNumSnodeTreesLlvm];
+
+  std::map<int, DeviceAllocation> snode_tree_id_to_device_alloc_;
 };
 
 }  // namespace taichi::lang