# Using full GPU node without MPI

**URL:** <https://gromacs.bioexcel.eu/t/using-full-gpu-node-without-mpi/7105>\
**Category:** User discussions\
**Tags:** mdrun\
**Created:** [August 30, 2023, 9:16am UTC](https://gromacs.bioexcel.eu/t/using-full-gpu-node-without-mpi/7105 "2023-08-30T09:16:32Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Hrishi](https://avatars.discourse-cdn.com/v4/letter/h/d2c977/32.png) [@Hrishi](https://gromacs.bioexcel.eu/u/Hrishi)\
**Post date:** [August 30, 2023, 9:16am UTC](https://gromacs.bioexcel.eu/t/using-full-gpu-node-without-mpi/7105/1 "2023-08-30T09:16:32Z")

</div>

GROMACS version: 2019  
GROMACS modification: Yes

Hello,

I am trying to run the gromacs on a multi-instance GPU (MIG). I tried several commands to run Gromacs but each time it used part of the GPU and not the full node.

```auto
1. gmx mdrun -v -deffnm md_0_10

2. gmx mdrun -ntmpi 6 -ntomp 12 -nb gpu -pme gpu -npme -1 -bonded gpu -v -deffnm md_0_10

3. gmx mdrun -gputasks 0001 -nb gpu -pme gpu -npme 1 -ntmpi 4 -v -deffnm md_0_10

4. mpirun -np 1 gmx_mpi mdrun -ntomp 6 -nb gpu -gputasks 00 -v -deffnm md_0_10

5. gmx mdrun -ntmpi 2 -nb gpu -pme gpu -bonded gpu -v -deffnm md_0_10

```

Has anyone faced the same problem earlier? Any help in this regard will be really helpful.

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<div class="post-metadata">

**Author:** ![pszilard](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pszilard/32/21_2.png) [@pszilard](https://gromacs.bioexcel.eu/u/pszilard)\
**Post date:** [August 30, 2023, 12:14pm UTC](https://gromacs.bioexcel.eu/t/using-full-gpu-node-without-mpi/7105/2 "2023-08-30T12:14:51Z")

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Hi,

Can you please clarify what exactly are you trying to accomplish? NVIDIA MIG is used to partition a GPU into multiple slices so independent work can progress concurrently (and in isolation). Are you trying to run many independent jobs on a single node?

Cheers,  
Szilárd

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<div class="post-metadata">

**Author:** ![Hrishi](https://avatars.discourse-cdn.com/v4/letter/h/d2c977/32.png) [@Hrishi](https://gromacs.bioexcel.eu/u/Hrishi)\
**Post date:** [August 30, 2023, 12:27pm UTC](https://gromacs.bioexcel.eu/t/using-full-gpu-node-without-mpi/7105/3 "2023-08-30T12:27:54Z")

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Hello @pszilard,

I am trying to run a simulation with Gromacs. I would like to run it with a higher speed so one of the platform team members told me to use a full GPU node to optimize the speed.

I just want an optimized speed for the simulation with this MIG architecture.  
I hope this clarifies your doubts. Please let me know if it answers your questions.

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<div class="post-metadata">

**Author:** ![pszilard](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pszilard/32/21_2.png) [@pszilard](https://gromacs.bioexcel.eu/u/pszilard)\
**Post date:** [September 11, 2023, 6:01pm UTC](https://gromacs.bioexcel.eu/t/using-full-gpu-node-without-mpi/7105/4 "2023-09-11T18:01:53Z")

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MIG will not improve the performance of a single simulation, it is can be useful for ensemble simulations, but even there the benefits are modest and MPS is more important; see this post from a few years ago:

> **[Maximizing GROMACS Throughput with Multiple Simulations per GPU Using MPS and...](https://developer.nvidia.com/blog/maximizing-gromacs-throughput-with-multiple-simulations-per-gpu-using-mps-and-mig)**
>
> In this post, we demonstrate the benefits of running multiple simulations per GPU for GROMACS.