# Error: CUDAOutofMemory on A30

**URL:** <https://pyfr.discourse.group/t/error-cudaoutofmemory-on-a30/1023>\
**Category:** Errors\
**Tags:** config, cuda\
**Created:** [7 February 2024 22:24 UTC](https://pyfr.discourse.group/t/error-cudaoutofmemory-on-a30/1023 "2024-02-07T22:24:03Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![wgbb](https://avatars.discourse-cdn.com/v4/letter/w/6f9a4e/32.png) [@wgbb](https://pyfr.discourse.group/u/wgbb)\
**Post date:** [8 February 2024 12:38 UTC](https://pyfr.discourse.group/t/error-cudaoutofmemory-on-a30/1023/3 "2024-02-08T12:38:35Z")

</div>

Hello, thank you very much for your reply.  
I have tried mpiexec -n 6 pyfr run -b cuda -p x.pyfrm x.ini by splitting the mesh first, but it gives an error raise

```auto
RuntimeError(f'Mesh has {nparts} partitions but running '
RuntimeError: Mesh has 6 partitions but running with 1 MPI ranks

```

I tried mpirun -n 6 with the same error, i think it’s a mpi4py error because i initially installed mpi4py via conda, but i got no clue about installing it via pip (cf. this [article](https://pyfr.discourse.group/t/gpu-parallelization-error-ranks-not-equal-to-gpu-number/661/20),). Finally I have a couple of questions I would like to ask you, thank you for your advice.  
Question 1: I think for gpu computing, one cpu core is enough, more cpu will add extra information communication, mpiexec -n 6 or mpirun are specifying 6 cpu cores, does it mean 6 gpu cards must have at least 6 cpu cores to use?  
Question 2: I tested mpi4yr with this code and didn’t get the expected results, so I decided it was an installation problem with mpi4py.  
from mpi4py import MPI

> if **name** == “ **main** ”.  
> comm = MPI.COMM\_WORLD  
> print(f “rank {comm.rank} of {comm.size}”)  
> comm.barrier()

> rank 0 of 1  
> rank 0 of 1  
> rank 0 of 1

I tried disabling the mpi environment in the cuda suite and installing it directly with the default mpi.

> ```
> nvc-Error-Unknown switch: -Wno-unused-result
> nvc-Error-Unknown switch: -fwrapv
> warning: build_ext: command '/opt/nvidia/hpc_sdk/Linux_x86_64/22.11/compilers/bin/nvc' failed with exit code 1
> warning: build_ext: building optional extension "mpi4py.dl" failed
> checking for MPI compile and link ...
> 
> ```

Unfortunately I couldn’t find the mpi4py.dl file

> find / -name mpi4py.dl  
> find: ‘/run/user/1001/doc’: Permission denied  
> find: ‘/run/user/1001/gvfs’: Permission denied

It’s worth noting that I’m using a single A30 GPU to compute the small memory example with no problem, just as I did with the A100.  
Regards, wgbb

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