ENH: add buddy alloctor Free

paddle/memory/detail/CMakeLists.txt

@@ -7,3 +7,6 @@ else(${WITH_GPU})
   cc_library(system_allocator SRCS system_allocator.cc DEPS gflags)
   cc_test(system_allocator_test SRCS system_allocator_test.cc DEPS system_allocator gflags)
 endif(${WITH_GPU})
+
+cc_library(metadata SRCS metadata.cc)
+cc_library(buddy_allocator SRCS buddy_allocator.cc)

paddle/memory/detail/buddy_allocator.cc

@@ -58,17 +58,16 @@ void* BuddyAllocator::Alloc(size_t unaligned_size) {
   // refill the pool if failure
   if (it == pool_.end()) {
     it = RefillPool();
+    // if still failure, fail fatally
+    if (it == pool_.end()) {
+      return nullptr;
+    }
   } else {
     DLOG(INFO) << " Allocation from existing memory block " << std::get<2>(*it)
                << " at address "
                << reinterpret_cast<MemoryBlock*>(std::get<2>(*it))->data();
   }
 
-  // if still failure, fail fatally
-  if (it == pool_.end()) {
-    return nullptr;
-  }
-
   total_used_ += size;
   total_free_ -= size;
 
@@ -76,6 +75,13 @@ void* BuddyAllocator::Alloc(size_t unaligned_size) {
   return reinterpret_cast<MemoryBlock*>(SplitToAlloc(it, size))->data();
 }
 
+void BuddyAllocator::Free(void* p) {
+  auto block = static_cast<MemoryBlock*>(p)->metadata();
+
+  // acquire the allocator lock
+  std::lock_guard<std::mutex> lock(mutex_);
+}
+
 void* BuddyAllocator::SystemAlloc(size_t size) {
   size_t index = 0;
   void* p = system_allocator_->Alloc(index, size);
@@ -140,17 +146,14 @@ BuddyAllocator::PoolSet::iterator BuddyAllocator::FindExistChunk(size_t size) {
 void* BuddyAllocator::SplitToAlloc(BuddyAllocator::PoolSet::iterator it,
                                    size_t size) {
   auto block = static_cast<MemoryBlock*>(std::get<2>(*it));
-
   pool_.erase(it);
 
   DLOG(INFO) << " Split block (" << block << ", " << block->total_size(cache_)
              << ") into";
-
   block->split(cache_, size);
 
   DLOG(INFO) << " Left block (" << block << ", " << block->total_size(cache_)
              << ")";
-
   block->set_type(cache_, MemoryBlock::ARENA_CHUNK);
 
   // the rest of memory if exist

paddle/memory/detail/buddy_allocator.h

@@ -14,16 +14,16 @@
 
 #pragma once
 
-#include "paddle/memory/detail/system_allocator.h"
 #include "paddle/memory/detail/metadata.h"
+#include "paddle/memory/detail/system_allocator.h"
 #include "paddle/platform/assert.h"
 #include "paddle/platform/cpu_info.h"
 #include "paddle/platform/gpu_info.h"
 
-#include <set>
 #include <mutex>
-#include <vector>
+#include <set>
 #include <unordered_map>
+#include <vector>
 
 namespace paddle {
 namespace memory {
@@ -57,9 +57,9 @@ class BuddyAllocator {
   /*! \brief If existing chunks are not suitable, refill pool */
   PoolSet::iterator RefillPool();
 
-  /** 
+  /**
    *  \brief Find the suitable chunk from existing pool
-   *  
+   *
    *  \param it   pool iterator which contains suitable block.
    *  \param size the size of allocation.
    */

paddle/memory/detail/memory_block.cc

@@ -0,0 +1,145 @@
+#include "paddle/memory/detail/memory_block.h"
+#include "paddle/platform/assert.h"
+
+namespace paddle {
+namespace memory {
+namespace detail {
+
+void MemoryBlock::init(MetadataCache& cache, Type t, size_t index, size_t size,
+                       void* left_buddy, void* right_buddy) {
+  cache.store(this,
+              MemoryBlockMetadata(t, index, size - overhead(), size,
+                                  static_cast<MemoryBlock*>(left_buddy),
+                                  static_cast<MemoryBlock*>(right_buddy)));
+}
+
+MemoryBlock::Type MemoryBlock::type(MetadataCache& cache) const {
+  return cache.load(this).type;
+}
+
+size_t MemoryBlock::size(MetadataCache& cache) const {
+  return cache.load(this).size;
+}
+
+size_t MemoryBlock::total_size(MetadataCache& cache) const {
+  return cache.load(this).total_size;
+}
+
+MemoryBlock* MemoryBlock::left_buddy(MetadataCache& cache) const {
+  return cache.load(this).left_buddy;
+}
+
+MemoryBlock* MemoryBlock::right_buddy(MetadataCache& cache) const {
+  return cache.load(this).right_buddy;
+}
+
+void MemoryBlock::split(MetadataCache& cache, size_t size) {
+  // make sure the split fits
+  assert(total_size(cache) >= size);
+
+  // bail out if there is no room for another partition
+  if (total_size(cache) - size <= overhead()) {
+    return;
+  }
+
+  // find the position of the split
+  void* right_partition = reinterpret_cast<uint8_t*>(this) + size;
+
+  size_t remaining_size = total_size(cache) - size;
+
+  // Add the new block as a buddy
+  auto metadata = cache.load(this);
+
+  // Write the metadata for the new block
+  auto new_block_right_buddy = metadata.right_buddy;
+
+  cache.store(static_cast<MemoryBlock*>(right_partition),
+              MemoryBlockMetadata(FREE_MEMORY, index(cache),
+                                  remaining_size - overhead(), remaining_size,
+                                  this, new_block_right_buddy));
+
+  metadata.right_buddy = static_cast<MemoryBlock*>(right_partition);
+  metadata.size = size - overhead();
+  metadata.total_size = size;
+
+  cache.store(this, metadata);
+
+  // Write metadata for the new block's right buddy
+  if (new_block_right_buddy != nullptr) {
+    auto buddy_metadata = cache.load(new_block_right_buddy);
+
+    buddy_metadata.left_buddy = static_cast<MemoryBlock*>(right_partition);
+
+    cache.store(new_block_right_buddy, buddy_metadata);
+  }
+}
+
+void MemoryBlock::merge(MetadataCache& cache, MemoryBlock* right_buddy) {
+  // only free blocks can be merged
+  assert(type(cache) == FREE_MEMORY);
+  assert(right_buddy->type(cache) == FREE_MEMORY);
+
+  auto metadata = cache.load(this);
+
+  // link this->buddy's buddy
+  metadata.right_buddy = right_buddy->right_buddy(cache);
+
+  // link buddy's buddy -> this
+  if (metadata.right_buddy != nullptr) {
+    auto buddy_metadata = cache.load(metadata.right_buddy);
+
+    buddy_metadata.left_buddy = this;
+
+    cache.store(metadata.right_buddy, buddy_metadata);
+  }
+
+  metadata.size += right_buddy->total_size(cache);
+  metadata.total_size += right_buddy->total_size(cache);
+
+  cache.store(this, metadata);
+  cache.store(right_buddy,
+              MemoryBlockMetadata(INVALID_MEMORY, 0, 0, 0, nullptr, nullptr));
+}
+
+void MemoryBlock::mark_as_free(MetadataCache& cache) {
+  // check for double free or corruption
+  assert(type(cache) != FREE_MEMORY);
+  assert(type(cache) != INVALID_MEMORY);
+
+  set_type(cache, FREE_MEMORY);
+}
+
+void MemoryBlock::set_type(MetadataCache& cache, Type t) {
+  auto metadata = cache.load(this);
+
+  metadata.type = t;
+
+  cache.store(this, metadata);
+}
+
+bool MemoryBlock::has_left_buddy(MetadataCache& cache) const {
+  return left_buddy(cache) != nullptr;
+}
+
+bool MemoryBlock::has_right_buddy(MetadataCache& cache) const {
+  return right_buddy(cache) != nullptr;
+}
+
+size_t MemoryBlock::index(MetadataCache& cache) const {
+  return cache.load(this).index;
+}
+
+void* MemoryBlock::data() const {
+  return const_cast<MemoryBlockMetadata*>(
+             reinterpret_cast<const MemoryBlockMetadata*>(this)) +
+         1;
+}
+
+MemoryBlock* MemoryBlock::metadata() const {
+  return const_cast<MemoryBlock*>(reinterpret_cast<const MemoryBlock*>(
+      reinterpret_cast<const MemoryBlockMetadata*>(this) - 1));
+}
+
+}  // detail
+}  // memory
+}  // paddle

paddle/memory/detail/memory_block.h

@@ -0,0 +1,97 @@
+/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License. */
+
+#pragma once
+
+#include "paddle/memory/detail/metadata.h"
+
+#include <cstddef>
+#include <unordered_map>
+
+namespace paddle {
+namespace memory {
+namespace detail {
+
+// Forward Declaration
+class Metadata;
+
+/*! \brief A class used to interpret the contents of a memory block */
+class MemoryBlock {
+ public:
+  // Unify the metadata format between GPU and CPU allocations
+  using MetadataCache = std::unordered_map<const MemoryBlock*, Metadata>;
+
+  enum Type {
+    FREE_CHUNK,    // memory is free and idle
+    ARENA_CHUNK,   // memory is being occupied
+    HUGE_CHUNK,    // memory is out of management
+    INVALID_CHUNK  // memory is invalid
+  };
+
+ public:
+  void init(MetadataCache& cache, Type t, size_t index, size_t size,
+            void* left_buddy, void* right_buddy);
+
+ public:
+  /*! \brief The type of the allocation */
+  Type type(MetadataCache& cache) const;
+
+  /*! \brief The size of the data region */
+  size_t size(MetadataCache& cache) const;
+
+  /*! \brief An index to track the allocator */
+  size_t index(MetadataCache& cache) const;
+
+  /*! \brief The total size of the block */
+  size_t total_size(MetadataCache& cache) const;
+
+  /*! \brief Check the left buddy of the block */
+  bool has_left_buddy(MetadataCache& cache) const;
+
+  /*! \brief Check the right buddy of the block */
+  bool has_right_buddy(MetadataCache& cache) const;
+
+  /*! \brief Get the left buddy */
+  MemoryBlock* left_buddy(MetadataCache& cache) const;
+
+  /*! \brief Get the right buddy */
+  MemoryBlock* right_buddy(MetadataCache& cache) const;
+
+ public:
+  /*! \brief Split the allocation into left/right blocks */
+  void split(MetadataCache& cache, size_t size);
+
+  /*! \brief Merge left and right blocks together */
+  void merge(MetadataCache& cache, MemoryBlock* right_buddy);
+
+  /*! \brief Mark the allocation as free */
+  void mark_as_free(MetadataCache& cache);
+
+  /*! \brief Change the type of the allocation */
+  void set_type(MetadataCache& cache, Type t);
+
+ public:
+  /*! \brief Get a pointer to the memory block's data */
+  void* data() const;
+
+  /*! \brief Get a pointer to the memory block's metadata */
+  MemoryBlock* metadata() const;
+
+ public:
+  static size_t overhead();
+};
+
+}  // namespace detail
+}  // namespace memory
+}  // namespace paddle

paddle/memory/detail/system_allocator.h

@@ -48,6 +48,7 @@ class GPUAllocator : public SystemAllocator {
   virtual void* Alloc(size_t& index, size_t size);
   virtual void Free(void* p, size_t size, size_t index);
   virtual bool UseGpu();
+
  private:
   size_t gpu_alloc_size_ = 0;
   size_t fallback_alloc_size_ = 0;