Profiling Deep Learning Applications¶

On Aurora, we can use the unitrace profiler from Intel to profile deep learning applications. Refer to the unitrace documentation page for details.

Example Usage¶

We can use unitrace to trace an application running on multiple ranks and multiple nodes. A simple example, where we use a wrapper script to trace rank 0 on each node of a 4-node job running a PyTorch application, is below.

There are several important shell variables in the wrapper, which may require modification:

#!/bin/bash
## This wrapper should be used with unitrace to trace in any number of nodes.
## The script for this example is set up to trace rank 0 of the first 4 nodes in the case of
## profiling a job running on more than 4 nodes.
FNAME_EXT=$(basename "$2")
FNAME="${FNAME_EXT%%.*}"

NNODES=`wc -l < $PBS_NODEFILE`

WORK_DIR=/path/to/the/Python/program
UNITRACE_DIR=/opt/aurora/24.180.1/support/tools/pti-gpu/063214e # (1)!
UNITRACE_LIB=${UNITRACE_DIR}/lib64
UNITRACE_BIN=${UNITRACE_DIR}/bin
UNITRACE_EXE=${UNITRACE_BIN}/unitrace
DTAG=$(date +%F_%H%M%S)
UNITRACE_OUTDIR=${WORK_DIR}/logs/unitrace_profiles/name_of_choice_json_n${NNODES}_${DTAG}/${FNAME}_n${NNODES}_${DTAG}
mkdir -p ${UNITRACE_OUTDIR}
UNITRACE_OPTS=" --ccl-summary-report --chrome-mpi-logging --chrome-sycl-logging \
--chrome-device-logging \
--chrome-ccl-logging --chrome-call-logging --chrome-dnn-logging --device-timing --host-timing \
--output-dir-path ${UNITRACE_OUTDIR} --output ${UNITRACE_OUTDIR}/UNITRACE_${FNAME}_n${NNODES}_${DTAG}.txt "  # (2)!

export LD_LIBRARY_PATH=${UNITRACE_LIB}:${UNITRACE_BIN}:$LD_LIBRARY_PATH

# Use $PMIX_RANK for MPICH and $SLURM_PROCID with srun.
PROFRANK=0 # (3)!
RANKCUTOFF=48 # (4)!

if [[ $PALS_LOCAL_RANKID -eq $PROFRANK ]] && [[ $PMIX_RANK -lt $RANKCUTOFF ]]; then
  echo "On rank $PMIX_RANK, collecting traces "
  $UNITRACE_EXE $UNITRACE_OPTS "$@"
else
  "$@"
fi

1. UNITRACE_DIR: This is the main unitrace directory, which may change after an update to the programming environment.
2. UNITRACE_OPTS: These are the options that unitrace uses to trace data at different levels. Based on the number of options, the sizes of the output profiles will vary. Usually, enabling more options leads to a larger profile (in terms of storage in MB).
3. PROFRANK: As implemented, this variable is set by the user to trace the rank of choice. For example, this wrapper will trace rank 0 on each node.
4. RANKCUTOFF: This variable is Aurora-specific. As we can run as many as 12 ranks per node (without using CCS), the first 4 nodes of a job will have 48 ranks running. This provides the upper cutoff of the label (in number) of ranks, beyond which unitrace will not trace any rank. A user can change the number according to the number of maximum ranks running per node to set up how many ranks to be traced. unitrace will produce a profile (json file, by default) per traced rank. This profile can be viewed using the Perfetto trace viewer.

Deployment¶

The wrapper above can be deployed using the following PBS job script:

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#!/bin/bash -x
#PBS -l select=4
#PBS -l place=scatter
#PBS -l walltime=00:10:00
#PBS -q debug-scaling
#PBS -l filesystems=<fs1:fs2>
#PBS -A <ProjectName>

WORK_DIR=/path/to/the/Python/program
UNITRACE_WRAPPER=${WORK_DIR}/unitrace_wrapper.sh

# MPI and OpenMP settings
NNODES=`wc -l < $PBS_NODEFILE`
NRANKS_PER_NODE=12

let NRANKS=${NNODES}*${NRANKS_PER_NODE}

module load frameworks/2024.2.1_u1

mpiexec --pmi=pmix -n ${NRANKS} -ppn ${NRANKS_PER_NODE} -l --line-buffer \
${UNITRACE_WRAPPER} python ${WORK_DIR}/application.py