DeepSpeed

The base conda environment on Polaris comes with Microsoft's DeepSpeed pre-installed. Instructions for using/cloning the base environment can be found here.

A batch submission script for the following example is available here.

We describe below the steps needed to get started with DeepSpeed on Polaris.

We focus on the cifar example provided in the DeepSpeedExamples repository, though this approach should be generally applicable for running any model with DeepSpeed support.

Running DeepSpeed on Polaris

Note

The instructions below should be run directly from a compute node.

Explicitly, to request an interactive job (from polaris-login):

qsub -A <project> -q debug-scaling -l select=2 -l walltime=01:00:00 -I

Refer to job scheduling and execution for additional information.

1. Load conda module and activate base environment:

   module load conda ; conda activate base
   

2. Clone microsoft/DeepSpeedExamples and navigate into the directory:

   git clone https://github.com/microsoft/DeepSpeedExamples.git
   cd DeepSpeedExamples/cifar
   

Launching DeepSpeed

Launching with MPICHLaunching with DeepSpeed

1. Get the total number of available GPUs:

   1. Count the number of lines in $PBS_NODEFILE (1 host per line)
   2. Count the number of GPUs available on the current host
   3. NGPUS="$((${NHOSTS}*${NGPU_PER_HOST}))"

      NHOSTS=$(wc -l < "${PBS_NODEFILE}")
      NGPU_PER_HOST=$(nvidia-smi -L | wc -l)
      NGPUS="$((${NHOSTS}*${NGPU_PER_HOST}))"
      

2. Launch with mpiexec:

   mpiexec \
     --verbose \
     --envall \
     -n "${NGPUS}" \
     --ppn "${NGPU_PER_HOST}" \
     --hostfile="${PBS_NODEFILE}" \
     python3 \
       cifar10_deepspeed.py \
       --deepspeed_config ds_config.json
   

1. Create a DeepSpeed compliant hostfile, specifying the hostname and number of GPUs (slots) for each of our available workers:

   cat $PBS_NODEFILE > hostfile
   sed -e 's/$/ slots=4/' -i hostfile
   

2. Create a .deepspeed_env containing the environment variables our workers will need access to:

   echo "PATH=${PATH}" >> .deepspeed_env
   echo "LD_LIBRARY_PATH=${LD_LIBRARY_PATH}" >> .deepspeed_env
   echo "http_proxy=${http_proxy}" >> .deepspeed_env
   echo "https_proxy=${https_proxy}" >> .deepspeed_env
   

Warning

The .deepspeed_env file expects each line to be of the form KEY=VALUE. Each of these will then be set as environment variables on each available worker specified in our hostfile.

We can then run the cifar10_deepspeed.py module using DeepSpeed:

deepspeed --hostfile=hostfile cifar10_deepspeed.py \
    --deepspeed \
    --deepspeed_config ds_config.json

AssertionError: Micro batch size per gpu: 0 has to be greater than 0

Depending on the details of your specific job, it may be necessary to modify the provided ds_config.json.

If you encounter an error:

x3202c0s31b0n0: AssertionError: Micro batch size per gpu: 0 has to be greater than 0

you can modify the "train_batch_size": 16 variable in the provided ds_config.json to the (total) number of available GPUs, and explicitly set "gradient_accumulation_steps": 1, as shown below.

$ export NHOSTS=$(wc -l < "${PBS_NODEFILE}")
$ export NGPU_PER_HOST=$(nvidia-smi -L | wc -l)
$ export NGPUS="$((${NHOSTS}*${NGPU_PER_HOST}))"
$ echo $NHOSTS $NGPU_PER_HOST $NGPUS
24 4 96
$ # replace "train_batch_size" with $NGPUS in ds_config.json
$ # and write to `ds_config-polaris.json`
$ sed \
    "s/$(cat ds_config.json| grep batch | cut -d ':' -f 2)/ ${NGPUS},/" \
    ds_config.json \
    > ds_config-polaris.json
$ cat ds_config-polaris.json
{
    "train_batch_size": 96,
    "gradient_accumulation_steps": 1,
    ...
}