Poseidon on a Private Cluster

Training

The executable for running Poseidon tasks is psd_run. Running psd_run -h should print this:

usage: psd_run [-h] [-c,--cluster_config CLUSTER_CONFIG]
               [-o,--out OUTPUT_FOLDER]
               cmd

psd_run runs Poseidon for distributed machine learning on a GPU cluster. The following are its command line arguments.

positional arguments:
  cmd

optional arguments:
  -h, --help            show this help message and exit
  -c,--cluster_config CLUSTER_CONFIG
                        configuration file for cluster environment: specify workers in each machine. See example:
                        {
                          "virtualenv": "/home/ubuntu/sandbox",
                          "username": "ubuntu",
                          "pem_file": "/path/to/pem-file.pem",
                          "master_node": "localhost",
                          "worker_nodes": [
                            "192.168.1.11",
                            "192.168.1.15"
                          ],
                          "server_nodes": [
                            "192.168.1.70",
                            "192.168.1.80"
                          ]
                        }
  -o,--out OUTPUT_FOLDER
                        output log folder

Setup

Say we wish to run Poseidon on two nodes, IP1 and IP2. We must create a config.json to specify our configurations. The runner psd_run uses ssh to communicate with the cluster, so certain options must be added, such as username. If you wish to use a virtualenv, you can specify it using the json as well. The path should correspond to $VIRTUAL_ENV environment variable (after virtualenv activate script has been run).

Note below that the virtualenv keyword is optional. Remove if you installed without virtualenv.

{
  "virtualenv": "/path/to/virtualenv",
  "username": "<cluster username>",
  "worker_nodes": [
    "<IP1>",
    "<IP2>"
  ],
  "server_nodes": [
    "<IP1>",
    "<IP2>"
  ]
}

For security reasons, the script does not allow passwords in ssh. Therefore, no-password ssh must be enabled for the username. On <IP1> (our master node), generate a key-pair. Then copy it onto <IP2>:

ssh-keygen
# Use defaults (press ENTER three times)

ssh-copy-id -i ~/.ssh/id_rsa.pub <cluster username>@<IP1>
ssh-copy-id -i ~/.ssh/id_rsa.pub <cluster username>@<IP2>
# Enter password

# Test, ssh should not prompt for a password
ssh <cluster username>@<IP2>
exit

Execution

We can now launch Poseidon with the following command:

psd_run -c config.json -o logs "python $TF_MODEL_HOME/tutorials/image/cifar10/cifar10_train.py --max_steps 1000"

Poseidon Logs

After running Poseidon, you can check the execution log poseidon_run.log in the same path you ran psd_run. There are also output log files for debugging and monitoring purposes created in poseidon_log_$TIMESTAMP_SUFFIX folder which will reside in a logs folder in your current directory (the -o directive).