Gromacs on Theta

What is Gromacs?

GROMACS is a versatile package to perform molecular dynamics, i.e. simulate the Newtonian equations of motion for systems with hundreds to millions of particles. It is primarily designed for biochemical molecules like proteins, lipids, and nucleic acids that have a lot of complicated bonded interactions, but since GROMACS is extremely fast at calculating the nonbonded interactions (that usually dominate simulations) many groups are also using it for research on non-biological systems, e.g. polymers.

Using GROMACS at ALCF

ALCF offers assistance with building binaries and compiling instructions for GROMACS. For questions, contact us at support@alcf.anl.gov.

Building Gromacs

Download latest source code: http://manual.gromacs.org/documentation/2022.1/download.html
tar -xzf gromacs-2022.1.tar.gz
cd gromacs-2022.1
mkdir build
module load cmake
module swap PrgEnv-intel PrgEnv-gnu/6.0.10

cmake -DCMAKE_C_COMPILER=cc -DCMAKE_CXX_COMPILER=CC \
      -DBUILD_SHARED_LIBS=OFF -DGMX_BUILD_OWN_FFTW=ON \
      -DCMAKE_INSTALL_PREFIX=/path-to/gromacs-2022.1/build \
      -DGMX_MPI=ON -DGMX_OPENMP=ON -DGMX_CYCLE_SUBCOUNTERS=ON -DGMX_GPU=OFF \
      -DGMX_BUILD_HELP=OFF -DGMX_HWLOC=OFF -DGMX_SIMD=AVX_512_KNL \
      -DGMX_OPENMP_MAX_THREADS=256

make –j 16
make install
The installed binary is build/bin/gmx_mpi.

Running Gromacs on Theta

Prebuilt Gromacs binaries can be found in the directory /soft/applications/gromacs/gromacs_theta.

A sample qsub script follows.

#!/bin/bash
#COBALT -n 1
#COBALT -t 30 
#COBALT -q debug-cache-quad 
#COBALT -project catalyst 
#COBALT --attrs mcdram=cache:numa=quad
#COBALT --attrs filesystems=home,theta-fs0

export GMX_MAXBACKUP=-1 

aprun -n64 -N64 --env OMP_NUM_THREADS=2 --cc depth -d 2 -j 2 \
      /soft/applications/gromacs/gromacs_theta/gmx_mpi.2022.1 mdrun \
      -dlb yes -resethway -pin on -v deffnm step5_1 -g test.log

We strongly suggest that users try combinations of different numbers of nodes, MPI ranks per node, and OMP threads per rank to find the optimal throughput for their particular workload.

The following is a representative benchmark for a system with 30,000 atoms generated on a single Theta node with above aprun command.

	Core time(sec)	Wall time(sec)	(%)
Time	9016.068	70.441	12799.4

	ns/day	hour/ns
Performance	61.330	0.391

Argonne Leadership Computing Facility