# Unbalanced CPU and GPU Utilization in GROMACS

**URL:** <https://gromacs.bioexcel.eu/t/unbalanced-cpu-and-gpu-utilization-in-gromacs/10509>\
**Category:** User discussions\
**Tags:** mdp-parameters, mdrun, simulation-setup\
**Created:** [November 8, 2024, 4:28pm UTC](https://gromacs.bioexcel.eu/t/unbalanced-cpu-and-gpu-utilization-in-gromacs/10509 "2024-11-08T16:28:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![ArtfullMaker](https://avatars.discourse-cdn.com/v4/letter/a/6a8cbe/32.png) [@ArtfullMaker](https://gromacs.bioexcel.eu/u/ArtfullMaker)\
**Post date:** [November 8, 2024, 4:28pm UTC](https://gromacs.bioexcel.eu/t/unbalanced-cpu-and-gpu-utilization-in-gromacs/10509/1 "2024-11-08T16:28:55Z")

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GROMACS version: 2024.4  
GROMACS modification: Yes  
What I can’t use my GPU?  
During the MD simulation, CPU usage reaches 100%, while GPU utilization increases to only 7%. Running the command `gmx mdrun -deffnm md_0_1 -v -nb gpu` or `gmx mdrun -deffnm md_0_1 -v` results in the same performance.

 ![](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/6/62111156b9e6c76c87b09cf6dd246760bc31fe70.png)  
 ![](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/6/69bbc64f8965b23fb90c3d242693bc901c32c970.png)

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**Author:** ![al42and](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/al42and/32/1393_2.png) [@al42and](https://gromacs.bioexcel.eu/u/al42and)\
**Post date:** [November 9, 2024, 11:14pm UTC](https://gromacs.bioexcel.eu/t/unbalanced-cpu-and-gpu-utilization-in-gromacs/10509/2 "2024-11-09T23:14:24Z")

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Hi!

“Utilization” of CPU or GPU is a rather meaningless metric and should be interpreted carefully. For starters, 100% CPU usage (as reported by, e.g., `top`) means a full utilization of _one core_, while a 100% GPU usage would mean full utilization of the entire GPU. Also, I only see Xwayland (graphics server) among the list of GPU processes; it does not look like GROMACS was running on the GPU when you took that screenshot.

Even with these caveats, it is not necessary that best performance equals highest utilization.

If you want some suggestions on improving performance, take a look at our [tuning guide](https://manual.gromacs.org/2024.4/user-guide/mdrun-performance.html) and check the performance counters reported at the end of the `md_0_1.log` file.

> Running the command `gmx mdrun -deffnm md_0_1 -v -nb gpu` or `gmx mdrun -deffnm md_0_1 -v` results in the same performance.

This is expected, since `-nb gpu` is the default when a GPU is detected.