text: /* Copyright 2015 The TensorFlow Authors. All Rights Reserved.
  
  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.
  ==============================================================================*/
  
  #ifndef TENSORFLOW_COMMON_RUNTIME_GPU_GPU_BFC_ALLOCATOR_H_
  #define TENSORFLOW_COMMON_RUNTIME_GPU_GPU_BFC_ALLOCATOR_H_
  
  #include <memory>
  #include <string>
  #include <unordered_map>
  #include <vector>
  
  #include "tensorflow/core/common_runtime/allocator_retry.h"
  #include "tensorflow/core/common_runtime/bfc_allocator.h"
  #include "tensorflow/core/common_runtime/gpu/gpu_id.h"
  #include "tensorflow/core/platform/stream_executor.h"
  #include "tensorflow/core/platform/thread_annotations.h"
  #include "tensorflow/core/platform/types.h"
  #include "tensorflow/core/protobuf/config.pb.h"
  
  namespace tensorflow {
  
  // A GPU memory allocator that implements a 'best-fit with coalescing'
  // algorithm.
  class GPUBFCAllocator : public BFCAllocator {
   public:
    // 'platform_gpu_id' refers to the ID of the GPU device within
    // the process and must reference a valid ID in the process.
    GPUBFCAllocator(PlatformGpuId platform_gpu_id, size_t total_memory,
                    const string& name);
    GPUBFCAllocator(PlatformGpuId platform_gpu_id, size_t total_memory,
                    const GPUOptions& gpu_options, const string& name);
    virtual ~GPUBFCAllocator() {}
  
    TF_DISALLOW_COPY_AND_ASSIGN(GPUBFCAllocator);
  };
  
  // Suballocator for GPU memory.
  class GPUMemAllocator : public SubAllocator {
   public:
    // Note: stream_exec cannot be null.
    explicit GPUMemAllocator(se::StreamExecutor* stream_exec,
                             bool use_unified_memory)
        : stream_exec_(stream_exec), use_unified_memory_(use_unified_memory) {
      CHECK(stream_exec_ != nullptr);
    }
    ~GPUMemAllocator() override {}
  
    void* Alloc(size_t alignment, size_t num_bytes) override {
      void* ptr = nullptr;
      if (num_bytes > 0) {
        if (use_unified_memory_) {
          ptr = stream_exec_->UnifiedMemoryAllocate(num_bytes);
        } else {
          ptr = stream_exec_->AllocateArray<char>(num_bytes).opaque();
        }
      }
      return ptr;
    }
  
    void Free(void* ptr, size_t num_bytes) override {
      if (ptr != nullptr) {
        if (use_unified_memory_) {
          stream_exec_->UnifiedMemoryDeallocate(ptr);
        } else {
          se::DeviceMemoryBase gpu_ptr(ptr);
          stream_exec_->Deallocate(&gpu_ptr);
        }
      }
    }
  
   private:
    se::StreamExecutor* stream_exec_;  // not owned, non-null
    const bool use_unified_memory_ = false;
  
    TF_DISALLOW_COPY_AND_ASSIGN(GPUMemAllocator);
  };
  
  }  // namespace tensorflow
  
  #endif  // TENSORFLOW_COMMON_RUNTIME_GPU_GPU_BFC_ALLOCATOR_H_
  