Spock (OLCF)

The Spock cluster is located at OLCF.


If you are new to this system, please see the following resources:

  • Spock user guide

  • Batch system: Slurm

  • Production directories:

    • $PROJWORK/$proj/: shared with all members of a project (recommended)

    • $MEMBERWORK/$proj/: single user (usually smaller quota)

    • $WORLDWORK/$proj/: shared with all users

    • Note that the $HOME directory is mounted as read-only on compute nodes. That means you cannot run in your $HOME.


Use the following commands to download the WarpX source code and switch to the correct branch:

git clone https://github.com/ECP-WarpX/WarpX.git $HOME/src/warpx

We use the following modules and environments on the system ($HOME/spock_warpx.profile).

Listing 20 You can copy this file from Tools/machines/spock-olcf/spock_warpx.profile.example.
# please set your project account
#export proj=<yourProject>

# required dependencies
module load cmake/3.20.2
module load craype-accel-amd-gfx908
module load rocm/4.3.0

# optional: faster builds
module load ccache
module load ninja

# optional: just an additional text editor
module load nano

# optional: an alias to request an interactive node for one hour
alias getNode="salloc -A $proj -J warpx -t 01:00:00 -p ecp -N 1"

# fix system defaults: do not escape $ with a \ on tab completion
shopt -s direxpand

# optimize CUDA compilation for MI100
export AMREX_AMD_ARCH=gfx908

# compiler environment hints
export CC=$ROCM_PATH/llvm/bin/clang
export CXX=$(which hipcc)
export LDFLAGS="-L${CRAYLIBS_X86_64} $(CC --cray-print-opts=libs) -lmpi"
# GPU aware MPI: ${PE_MPICH_GTL_DIR_gfx908} -lmpi_gtl_hsa

We recommend to store the above lines in a file, such as $HOME/spock_warpx.profile, and load it into your shell after a login:

source $HOME/spock_warpx.profile

Then, cd into the directory $HOME/src/warpx and use the following commands to compile:

cd $HOME/src/warpx
rm -rf build

cmake -S . -B build -DWarpX_DIMS="1;2;3" -DWarpX_COMPUTE=HIP -DWarpX_PSATD=ON -DAMReX_AMD_ARCH=gfx908 -DMPI_CXX_COMPILER=$(which CC) -DMPI_C_COMPILER=$(which cc) -DMPI_COMPILER_FLAGS="--cray-print-opts=all"
cmake --build build -j 10

The general cmake compile-time options apply as usual.

That’s it! A 3D WarpX executable is now in build/bin/ and can be run with a 3D example inputs file. Most people execute the binary directly or copy it out to a location in $PROJWORK/$proj/.


MI100 GPUs (32 GB)

After requesting an interactive node with the getNode alias above, run a simulation like this, here using 4 MPI ranks:

srun -n 4 -c 2 --ntasks-per-node=4 ./warpx inputs

Or in non-interactive runs started with sbatch:

Listing 21 You can copy this file from Tools/machines/spock-olcf/spock_mi100.sbatch.

#SBATCH -A <project id>
#SBATCH -J warpx
#SBATCH -o %x-%j.out
#SBATCH -t 00:10:00
#SBATCH -p ecp

srun -n 4 -c 2 --ntasks-per-node=4 ./warpx inputs > output.txt

We can currently use up to 4 nodes with 4 GPUs each (maximum: -N 4 -n 16).


For post-processing, most users use Python via OLCFs’s Jupyter service (Docs).

Please follow the same guidance as for OLCF Summit post-processing.