[ET-VK] Adding MemoryPool class to allocate chunks of memory and use it for smaller allocations.

Differential Revision: [D67220112](https://our.internmc.facebook.com/intern/diff/D67220112/)

ghstack-source-id: 258102837
Pull Request resolved: #7338

Author: trivedivivek

backends/vulkan/runtime/utils/MemoryPool.cpp

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <executorch/backends/vulkan/runtime/utils/MemoryPool.h>
+
+namespace vkcompute::utils {
+
+// constexpr const size_t kUniquePtrAllocatorInitBlockSize = 16 * 1024;
+// constexpr const size_t kUniquePtrAllocatorAlignment = 8;
+
+// void MemoryPool::reset() noexcept(false) {
+//   for (auto& block : blocks_) {
+//     block.reset();
+//   }
+//   currentBlockIndex_ = 0;
+// }
+
+// MemoryPool::BlockInfo::BlockInfo(BlockInfo&& other) noexcept {
+//   *this = other;
+// }
+
+// MemoryPool::BlockInfo& MemoryPool::BlockInfo::operator=(
+//     MemoryPool::BlockInfo&& other) noexcept {
+//   totalCapacity_ = other.totalCapacity_;
+//   currentCapacity_ = other.currentCapacity_;
+//   data_ = std::move(other.data_);
+//   return *this;
+// }
+
+// MemoryPool::BlockInfo& MemoryPool::BlockInfo::operator=(
+//     MemoryPool::BlockInfo& other) {
+//   totalCapacity_ = other.totalCapacity_;
+//   currentCapacity_ = other.currentCapacity_;
+//   data_ = std::move(other.data_);
+//   return *this;
+// }
+
+// void MemoryPool::BlockInfo::reset() noexcept(false) {
+//   currentCapacity_ = totalCapacity_;
+// }
+
+// void* MemoryPool::alloc(size_t size) {
+//   size = ((size + kUniquePtrAllocatorAlignment - 1) /
+//           kUniquePtrAllocatorAlignment) *
+//       kUniquePtrAllocatorAlignment;
+//   if (blocks_.empty() || blocks_[currentBlockIndex_].currentCapacity_ < size)
+//   {
+//     //  find a block that has enough space
+//     bool found = false;
+//     for (uint32_t i = currentBlockIndex_ + 1; i < blocks_.size(); ++i) {
+//       if (blocks_[i].currentCapacity_ >= size) {
+//         currentBlockIndex_ = i;
+//         found = true;
+//         break;
+//       }
+//     }
+
+//     if (!found) { // no block has enough space, create a new one
+//       auto& blockInfo = blocks_.emplace_back(BlockInfo{});
+//       blockInfo.totalCapacity_ =
+//           std::max(size, kUniquePtrAllocatorInitBlockSize);
+//       blockInfo.currentCapacity_ = blockInfo.totalCapacity_;
+//       blockInfo.data_ =
+//       std::make_unique<uint8_t[]>(blockInfo.totalCapacity_);
+//       currentBlockIndex_ = blocks_.size() - 1;
+//     }
+//   }
+
+//   auto& blockInfo = blocks_[currentBlockIndex_];
+//   auto ret = blockInfo.data_.get() +
+//       (blockInfo.totalCapacity_ - blockInfo.currentCapacity_);
+//   // blockInfo.allocations_.push_back(reinterpret_cast<AllocatorBase*>(ret));
+//   blockInfo.currentCapacity_ -= size;
+//   return ret;
+// }
+
+} // namespace vkcompute::utils

backends/vulkan/runtime/utils/MemoryPool.h

@@ -0,0 +1,138 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <memory>
+#include <vector>
+
+namespace vkcompute::utils {
+
+/**
+ * @class This class is designed to improving memory allocation for unique
+ *pointer allocations for a class or derivatives of a class. Allocation is done
+ *in blocks and every unique pointer allocation takes chunk from the block.
+ *
+ * This class is designed to be a fast alternative to calling new and delete for
+ *every unique pointer. Its speed is mainly due to the fact that it allocates
+ *memory in successive location in a block and does not try to reuse indivudual
+ *memory location after its deallocated.
+ **/
+template <class BaseType, const uint32_t kInitBlockSize = 4 * 1024, const uint32_t kAllocAlignment = 16>
+class MemoryPool final {
+ public:
+  MemoryPool() = default;
+  virtual ~MemoryPool() = default;
+
+  struct Deleter final // deleter
+  {
+    inline void operator()(BaseType* obj) const {
+      if (obj) {
+        obj->~BaseType();
+      }
+    }
+  };
+
+  struct alignas(kAllocAlignment) AlignedStruct final {
+    uint8_t data[kAllocAlignment];
+  };
+
+  /**
+   * @brief Allocates a new object of Type type by allocating memory from an
+   *allocation block and returns a unique pointer to it.
+   * @param ref - reference object to construct object from.
+   **/
+  template <class Type>
+  std::unique_ptr<BaseType, MemoryPool::Deleter> make_unique(Type&& ref) {
+    static_assert(
+        kAllocAlignment >= alignof(Type),
+        "Memory pool can only safely allocate object of alignment kAllocAlignment or less");
+    auto ptr = std::unique_ptr<BaseType, MemoryPool::Deleter>(
+        new (alloc(sizeof(Type))) Type(std::move(ref)), MemoryPool::Deleter());
+    return ptr;
+  }
+
+  /**
+   * @brief Reset all block allocation info, so it can be reused.
+   * Call this function only after all the unique pointers allcated by this
+   * block have been deallocated. Else it may result in memory leaks.
+   **/
+  void reset() noexcept(false) {
+    for (auto& block : blocks_) {
+      block.reset();
+    }
+    currentBlockIndex_ = 0;
+  }
+
+ private:
+  struct BlockInfo {
+    uint32_t totalCapacity_ = 0;
+    uint32_t currentCapacity_ = 0;
+    std::unique_ptr<AlignedStruct[]> data_{};
+
+    BlockInfo() = default;
+    ~BlockInfo() = default;
+
+    BlockInfo(BlockInfo&& other) noexcept {
+      *this = other;
+    }
+
+    BlockInfo& operator=(BlockInfo&& other) noexcept {
+      totalCapacity_ = other.totalCapacity_;
+      currentCapacity_ = other.currentCapacity_;
+      data_ = std::move(other.data_);
+      return *this;
+    }
+
+    BlockInfo& operator=(BlockInfo& other) {
+      totalCapacity_ = other.totalCapacity_;
+      currentCapacity_ = other.currentCapacity_;
+      data_ = std::move(other.data_);
+      return *this;
+    }
+
+    void reset() noexcept(false) {
+      currentCapacity_ = totalCapacity_;
+    }
+  };
+
+  std::vector<BlockInfo> blocks_{};
+  uint32_t currentBlockIndex_ = 0;
+
+  void* alloc(size_t size) {
+    size =
+        ((size + kAllocAlignment - 1) / kAllocAlignment) *
+        kAllocAlignment;
+    if (blocks_.empty() ||
+        blocks_[currentBlockIndex_].currentCapacity_ < size) {
+      //  find a block that has enough space
+      bool found = false;
+      for (uint32_t i = currentBlockIndex_ + 1; i < blocks_.size(); ++i) {
+        if (blocks_[i].currentCapacity_ >= size) {
+          currentBlockIndex_ = i;
+          found = true;
+          break;
+        }
+      }
+
+      if (!found) { // no block has enough space, create a new one
+        auto& blockInfo = blocks_.emplace_back(BlockInfo{});
+        blockInfo.totalCapacity_ = std::max(size, kInitBlockSize);
+        blockInfo.currentCapacity_ = blockInfo.totalCapacity_;
+        blockInfo.data_ = std::make_unique<AlignedStruct[]>((blockInfo.totalCapacity_ + sizeof(AlignedStruct) - 1) / sizeof(AlignedStruct));
+        currentBlockIndex_ = blocks_.size() - 1;
+      }
+    }
+
+    auto& blockInfo = blocks_[currentBlockIndex_];
+    auto ret = blockInfo.data_.get()->data + (blockInfo.totalCapacity_ - blockInfo.currentCapacity_);
+    blockInfo.currentCapacity_ -= size;
+    return ret;
+  }
+};
+
+} // namespace vkcompute::utils