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Paddle/paddle/fluid/platform/collective_helper.h

118 lines
3.8 KiB

// 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
#if defined(PADDLE_WITH_CUDA) && !defined(_WIN32)
#include <map>
#include <memory>
#include <string>
#include <vector>
#include "boost/variant.hpp"
#include "paddle/fluid/framework/data_type.h"
#include "paddle/fluid/platform/device_context.h"
#include "paddle/fluid/platform/enforce.h"
namespace paddle {
namespace platform {
// In order to apply hierarchical communication with NCCL, we need
// a communication ring contains NCCL communicators associated to a global
// ncclUniqueId. E.g. for a hierarchical case,
//
// 11 - 12 21 - 22
// | | | |
// 13 - 14 - 23 - 24
// | |
// 31 - 32 - 41 - 42
// | | | |
// 33 - 34 43 - 44
//
// we group (14,23,32,41) as the top, and (11,12,13,14), (21,22,23,24),
// (31,32,33,34), (41,42,43,44) as bottoms respectively.
//
// We could also use a single communication ring for the flatten case
//
// The NCCLComm instance is created and reversed in the NCCLCommContext
// singleton with a global user specified group id.
class NCCLComm {
public:
virtual int ring_id() const = 0;
virtual int nranks() const = 0;
virtual int rank() const = 0;
virtual int device_id() const = 0;
virtual ncclComm_t comm() const = 0;
virtual cudaStream_t stream() const = 0;
virtual ~NCCLComm() = default;
};
// A singleton NCCL communicator context reserves communication ring ids
class NCCLCommContext {
public:
static NCCLCommContext& Instance() {
static NCCLCommContext comm_ctx;
return comm_ctx;
}
NCCLComm* CreateNCCLComm(ncclUniqueId* nccl_id, int nranks, int rank,
int dev_id, int ring_id = 0);
void CreateAllNCCLComms(const std::vector<int>& dev_ids, int ring_id = 0);
// retrieve a communicator by the ring id in multiprocessing mode
NCCLComm* Get(int ring_id) const {
PADDLE_ENFORCE_GT(comm_map_.count(ring_id), 0,
"comunicator in ring id %d has not been initialized",
ring_id);
PADDLE_ENFORCE_EQ(comm_map_.at(ring_id).size(), 1,
"you should specify a device id to retrieve from "
"multiple communicators");
return comm_map_.at(ring_id).begin()->second.get();
}
// retrieve a communicator by the ring id and the device id
NCCLComm* Get(int ring_id, int dev_id) const {
PADDLE_ENFORCE_GT(comm_map_.count(ring_id), 0,
"comunicator of ring id %d has not been initialized",
ring_id);
PADDLE_ENFORCE_GT(
comm_map_.at(ring_id).count(dev_id), 0,
"comunicator at device id %d has not been initialized in ring %d",
dev_id, ring_id);
return comm_map_.at(ring_id).at(dev_id).get();
}
// retrieve a communicator by the ring id and place
NCCLComm* Get(int ring_id, Place place) const {
return Get(ring_id, boost::get<CUDAPlace>(place).device);
}
private:
std::once_flag once_flag_;
std::mutex comm_map_mutex_;
// ring id to dev-NCCLComm
std::map<int, std::map<int, std::unique_ptr<NCCLComm>>> comm_map_;
void ReleaseNCCLComms();
NCCLCommContext() = default;
DISABLE_COPY_AND_ASSIGN(NCCLCommContext);
};
} // namespace platform
} // namespace paddle
#endif