How to change CUDA version - linux

Question

I met this error when compiling a modified caffe version.
OpenCV static library was compiled with CUDA 7.5 support. Please, use the same version or rebuild OpenCV with CUDA 8.0
I have some old code may not compatible with CUDA8.0, so I want to change my cuda version for this error.
I modified my ~/.bash_profile like this
# export PYTHONPATH=$PYTHONPATH:/usr/local/cuda-8.0/lib64/
# export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/cuda-8.0/lib64
export PYTHONPATH=$PYTHONPATH:/usr/local/cuda-7.5/targets/x86_64-linux/lib/
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/cuda-7.5/targets/x86_64-linux/lib/
But it did't work. Still the same error. What should I do? Thanks.

Answer 1

Change your CUDA soft link to point on your desired CUDA version. For example:
ll /usr/local/cuda
lrwxrwxrwx 1 root root 19 Sep 06 2017 /usr/local/cuda -> /usr/local/cuda-8.0/
Simply relink it with
Update:
If the symlink already exists, use this other command:
[jalal#goku ~]$ ls /usr/local/cuda
lrwxrwxrwx. 1 root root 20 Sep 14 08:03 /usr/local/cuda -> /usr/local/cuda-10.2
[jalal#goku ~]$ sudo ln -sfT /usr/local/cuda/cuda-11.1/ /usr/local/cuda
[jalal#goku ~]$ ls /usr/local/cuda
lrwxrwxrwx. 1 root root 26 Sep 14 13:25 /usr/local/cuda -> /usr/local/cuda/cuda-11.1/
ln -s /usr/local/cuda-7.5 /usr/local/cuda
(With the proper installation location)

Answer 2

Perhaps cleaner:
sudo update-alternatives --display cuda
sudo update-alternatives --config cuda

Answer 3

Maybe a bit late, but I thought it might still be helpful for anyone who comes across this question. I wrote a simple bash script for switching to a different version of CUDA within the current bash session: https://github.com/phohenecker/switch-cuda

Answer 4

This solution explains how you can have multiple different cuda versions installed, i.e. 10.2, 11.3 and 11.6 and switch between them. It's an extension of #w.t and makes use of update-alternatives.
Afaik, after cuda 11.x the installations on Ubuntu 20.04 cuda installations will be added to the update-alternatives maintenance automatically.
Let's say you installed cuda 10.2, cuda 11.3 and cuda 11.6 (following the official nvidia installation guide: https://docs.nvidia.com/cuda/cuda-installation-guide-linux/index.html). They will all reside in:
/usr/local/cuda-10.2/...
/usr/local/cuda-11.3/...
/usr/local/cuda-11.6/...
Your update-alternatives will have two entries:
$ sudo update-alternatives --query cuda
...
/usr/local/cuda-11-3 - priority 113
/usr/local/cuda-11-6 - priority 116
Solution 1: If you want to make use of the update-alternatives make sure that your cuda symbolic link points to /etc/alternatives/cuda.
# Change the symbolic link target.
$ sudo ln -sfT /etc/alternatives/cuda /usr/local/cuda
# Check the path.
$ ll /usr/local/cuda
lrwxrwrwrwx 1 root root /usr/local/cuda -> /etc/alternatives/cuda/
Now, all that is left is to make sure /etc/alternatives/cuda points to the version you want to use, e.g. 11.3.
You can make that update with:
$ sudo update-alternatives --config cuda
and follow the instructions to change the version.
Check the path:
$ ll /etc/alternatives/cuda
lrwrwrwrwx root root /etc/alternatives -> /usr/local/cuda-11.3
almost done.
And always make sure to load the correct library PATHs in your ~/.bashrc.
Solution 2:
Directly set your /usr/local/cuda symbolic link to the correct version.
$ ln -sfT /usr/local/cuda-11.3 /usr/local/cuda
Reboot your machine and double check everything is set properly:
$ nvcc -V
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2021 NVIDIA Corporation
Built on Mon_May3 19:15:14_PDT_2021
Cuda compilation tools, release 11.3 V11.3.109
Build cuda 11.3.r11.3/compiler.29920130_0

Answer 5

I solved the problem finally.
Modifying ~/.bash_profile to change the path to CUDA is the correct way. But when you changed the file, you need to relaunch the bash.
Simply source ~/.bash_profile won't work. Because source will only append the content in the file to the already existed path rather than cover it.

Answer 6

I switched from cuda 10.2 to 11.7. export PATH=/etc/alternatives/cuda/bin:$PATH did the trick for me. I found the solution in this thread: https://stackoverflow.com/a/40599478/7924573