managed_memory_resource.hpp

/*
 * Copyright (c) 2019-2021, NVIDIA CORPORATION.
 *
 * 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 <rmm/mr/device/device_memory_resource.hpp>
 
#include <rmm/cuda_stream_view.hpp>
#include <rmm/detail/error.hpp>
 
#include <cstddef>
 
namespace rmm::mr {
class managed_memory_resource final : public device_memory_resource {
 public:
  managed_memory_resource()                               = default;
  ~managed_memory_resource() override                     = default;
  managed_memory_resource(managed_memory_resource const&) = default;
  managed_memory_resource(managed_memory_resource&&)      = default;
  managed_memory_resource& operator=(managed_memory_resource const&) = default;
  managed_memory_resource& operator=(managed_memory_resource&&) = default;
 
  [[nodiscard]] bool supports_streams() const noexcept override { return false; }
 
  [[nodiscard]] bool supports_get_mem_info() const noexcept override { return true; }
 
 private:
  void* do_allocate(std::size_t bytes, cuda_stream_view) override
  {
    // FIXME: Unlike cudaMalloc, cudaMallocManaged will throw an error for 0
    // size allocations.
    if (bytes == 0) { return nullptr; }
 
    void* ptr{nullptr};
    RMM_CUDA_TRY_ALLOC(cudaMallocManaged(&ptr, bytes));
    return ptr;
  }
 
  void do_deallocate(void* ptr, std::size_t, cuda_stream_view) override
  {
    RMM_ASSERT_CUDA_SUCCESS(cudaFree(ptr));
  }
 
  [[nodiscard]] bool do_is_equal(device_memory_resource const& other) const noexcept override
  {
    return dynamic_cast<managed_memory_resource const*>(&other) != nullptr;
  }
 
  [[nodiscard]] std::pair<std::size_t, std::size_t> do_get_mem_info(
    cuda_stream_view stream) const override
  {
    std::size_t free_size{};
    std::size_t total_size{};
    RMM_CUDA_TRY(cudaMemGetInfo(&free_size, &total_size));
    return std::make_pair(free_size, total_size);
  }
};
 
}  // namespace rmm::mr