all_reduce_op_handle.h

//   Copyright (c) 2018 PaddlePaddle 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.

#pragma once

#include <string>
#include <vector>

#include "paddle/fluid/framework/details/op_handle_base.h"
#include "paddle/fluid/framework/lod_tensor.h"
#include "paddle/fluid/framework/scope.h"
#if defined(PADDLE_WITH_CUDA) && !defined(_WIN32)
#include "paddle/fluid/platform/nccl_helper.h"
#endif

namespace paddle {
namespace framework {
namespace details {

#if defined(PADDLE_WITH_CUDA) && !defined(_WIN32)
constexpr char g_dgc_counter_name[] = "__g_dgc_counter__";
constexpr char g_dgc_rampup_begin_step[] = "__g_rampup_begin_step__";
constexpr char g_dgc_encoded[] = "__dgc_encoded__";
constexpr char g_dgc_k[] = "__dgc_k__";
#endif

struct AllReduceOpHandle : public OpHandleBase {
#if defined(PADDLE_WITH_CUDA) && !defined(_WIN32)
  AllReduceOpHandle(ir::Node *node, const std::vector<Scope *> &local_scopes,
                    const std::vector<platform::Place> &places,
                    const platform::NCCLContextMap *ctxs,
                    bool is_encoded = false, int nranks = -1);
#else
  AllReduceOpHandle(ir::Node *node, const std::vector<Scope *> &local_scopes,
                    const std::vector<platform::Place> &places);
#endif
  std::string Name() const override;

  // Delay and buffer nccl_all_reduce together can significantly increase
  // performance. Disable this feature by returning false.
  bool IsMultiDeviceTransfer() override { return true; };

 protected:
  void RunImpl() override;

 private:
  std::vector<Scope *> local_scopes_;
  std::vector<platform::Place> places_;
#if defined(PADDLE_WITH_CUDA) && !defined(_WIN32)
  void RunImplEncoded();
  const platform::NCCLContextMap *nccl_ctxs_;
  bool is_encoded_{false};
  int nranks_{-1};
  int GetKValue(const std::string &grad_name);
#endif
  void RunImplNormal();
  bool IsEncoded();
};

}  // namespace details
}  // namespace framework
}  // namespace paddle