Gromacs run only on 1 processor without using all threads

User discussions
1

GROMACS version: 2023.3
GROMACS modification: No
Hello Gromacs users,

I built Gromacs 2023.3 on Ubuntu 24.04 with pre-installed libomp-dev using such code

cmake .. -DGMX_GPU=CUDA -DGMX_PREFER_STATIC_LIBS=OFF -DGMXAPI=OFF -DGMX_BUILD_OWN_FFTW=ON -DCUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda -DCMAKE_INSTALL_PREFIX=/home/xxx/progs/gromacs_2023_3 -DGMX_DEFAULT_SUFFIX=OFF -DGMX_BINARY_SUFFIX=_2023_3 -DGMX_LIBS_SUFFIX=_2023_3 make -j 20 make install
The installation of Gromacs did not cause any problems. However, when I run gromacs:

gmx_2023_3 mdrun -v -deffnm press600 -bonded gpu -nb gpu -pme gpu -s topol_600.tpr -cpi press600.cpt

In the log file, I see that

PME tasks will do all aspects on the GPU
Using 1 MPI thread
Using 32 OpenMP threads

Nevertheless, the nvtop or glances only show that 1 processor run on maximum 100% performance.
Could you please suggest a solution to this problem.

2

can you share your system information and log file. You have offloaded all the calculations to the GPU, though

3

When everything runs on the GPU, only one thread will be active most of the time on the CPU, so most cores will be idle.