Ubuntu16.04 安装nccl+openmpi+horovod

1.安装nccl

官网教程：https://docs.nvidia.com/deeplearning/nccl/install-guide/index.html#down

1.Install the repository.
选择local或者network其中一种安装方式
For the local NCCL repository:
sudo dpkg -i nccl-repo-<version>.deb
For the network repository:
sudo dpkg -i nvidia-machine-learning-repo-<version>.deb

2.Update the APT database:
sudo apt update

3.Install the libnccl2 package with APT. Additionally, if you need to compile applications with NCCL, you can install the libnccl-dev package as well:
Note: If you are using the network repository, the following command will upgrade CUDA to the latest version.
sudo apt install libnccl2 libnccl-dev
If you prefer to keep an older version of CUDA, specify a specific version, for example:
sudo apt install libnccl2=2.4.8-1+cuda10.0 libnccl-dev=2.4.8-1+cuda10.0

也可以选择使用nccl源码编译安装：https://github.com/NVIDIA/nccl

1.1在使用 sudo apt update指令时提示以下错误：

Hit:31 http://cn.archive.ubuntu.com/ubuntu xenial-backports InRelease
Err:25 https://developer.download.nvidia.cn/compute/cuda/repos/ubuntu1604/x86_64  InRelease
  Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?)
Ign:27 https://developer.download.nvidia.cn/compute/machine-learning/repos/ubuntu1604/x86_64  InRelease
Hit:32 https://developer.download.nvidia.cn/compute/machine-learning/repos/ubuntu1604/x86_64  Release
Fetched 32 B in 30s (1 B/s)  
Reading package lists... Done
E: Failed to fetch http://developer.download.nvidia.com/compute/cuda/repos/ubuntu1604/x8