# Unable to use multi-gpu rendering with pvbatch using EGL ParaView

**URL:** https://discourse.paraview.org/t/unable-to-use-multi-gpu-rendering-with-pvbatch-using-egl-paraview/11945
**Category:** ParaView Support
**Created:** [April 21, 2023, 9:29am UTC](https://discourse.paraview.org/t/unable-to-use-multi-gpu-rendering-with-pvbatch-using-egl-paraview/11945 "2023-04-21T09:29:16Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![ssss](https://discourse.paraview.org/user_avatar/discourse.paraview.org/ssss/32/2358_2.png) [@ssss](https://discourse.paraview.org/u/ssss)
#### Post date: [April 21, 2023, 9:29am UTC](https://discourse.paraview.org/t/unable-to-use-multi-gpu-rendering-with-pvbatch-using-egl-paraview/11945/1 "2023-04-21T09:29:17Z")

</div>

When using `pvbatch` with multiple GPUs, `nvidia-smi` reports that only GPU0 is being used. To ease reproducing this on Kitware’s side, here are some steps and scripts that we used:

- I handcrafted a simple python script called `test.py`.

```auto
from paraview import simple

renderViewSettings = simple.GetSettingsProxy('RenderViewSettings')

# Properties modified on renderViewSettings
renderViewSettings.RemoteRenderThreshold = 0.0
a = simple.Cone()
simple.Show(a)
simple.Render()
simple.SaveScreenshot("/tmp/hello.png")

import time
time.sleep(20)

```

- Now, I created a headless EGL `pvserver` using

```auto
mpiexec \
-np 2 -x NVIDIA_VISIBLE_DEVICES=0,1,2,3 ./pvserver --mpi --force-offscreen-rendering --displays 0 : \
-np 2 -x NVIDIA_VISIBLE_DEVICES=0,1,2,3 ./pvserver --mpi --force-offscreen-rendering --displays 1 : \
-np 2 -x NVIDIA_VISIBLE_DEVICES=0,1,2,3 ./pvserver --mpi --force-offscreen-rendering --displays 2

```

- I then connected to this `pvserver` using a QT `paraview` binary, ran `test.py`, and saw 3 GPUs being used in `nvidia-smi`. Hence, `pvserver` seems to be working fine.
- I tried then with `pvbatch` using

```auto
mpiexec \
-np 2 -x NVIDIA_VISIBLE_DEVICES=0,1,2,3 ./pvbatch --mpi --force-offscreen-rendering --displays 0 -- ./test.py : \
-np 2 -x NVIDIA_VISIBLE_DEVICES=0,1,2,3 ./pvbatch --mpi --force-offscreen-rendering --displays 1 -- ./test.py : \
-np 2 -x NVIDIA_VISIBLE_DEVICES=0,1,2,3 ./pvbatch --mpi --force-offscreen-rendering --displays 2 -- ./test.py 

```

and I only see GPU with 0 index being used.

- Does anyone know a solution for this issue?
- If not, is there an easy way to replace a pvbatch-like workflow with a pvserver-based one?

Thank you!

---

<div class="post-metadata">

### Author: ![Francois\_Mazen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/francois_mazen/32/6483_2.png) [@Francois\_Mazen](https://discourse.paraview.org/u/Francois_Mazen)
#### Post date: [April 24, 2023, 11:23am UTC](https://discourse.paraview.org/t/unable-to-use-multi-gpu-rendering-with-pvbatch-using-egl-paraview/11945/2 "2023-04-24T11:23:50Z")

</div>

Have you tried the `-bynode` option of OpenMPI or `--map-by node` of MPICH?  
This is the usual way to map MPI processes to computation nodes with multiple GPU.

---

<div class="post-metadata">

### Author: ![ssss](https://discourse.paraview.org/user_avatar/discourse.paraview.org/ssss/32/2358_2.png) [@ssss](https://discourse.paraview.org/u/ssss)
#### Post date: [April 24, 2023, 4:14pm UTC](https://discourse.paraview.org/t/unable-to-use-multi-gpu-rendering-with-pvbatch-using-egl-paraview/11945/3 "2023-04-24T16:14:20Z")

</div>

@Francois_Mazen the same command works in pvserver but not in pvbatch and, also, these tests were done in a single node. Hence, I don’t think that it’s an MPI issue. It seems to me that it’s more related to how pvbatch works in MPI.