How to enable NVIDIA Nsight Compute CLI in Fedora
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When working with CUDA, NVIDIA’s Nsight Compute CLI (ncu) is an indispensable command-line tool for profiling your CUDA applications. It lets you peek under the hood to see exactly how your code is performing on the GPU.
For instance, you can easily profile a CUDA application with a command like this:
ncu -o myProfileData --set full ./cuda_sample
The command above generates a file myProfileData.ncu-rep which we can inspect with NVIDIA Nsight GUI to see all the profiled data.
However, to set it up in Linux can be a bit tricky.
Setting It Up on Linux
The first time you use ncu, you might get the following error:
The user does not have permission to access NVIDIA GPU Performance Counters on the target device 0. For instructions on enabling permissions and to get more information see https://developer.nvidia.com/ERR_NVGPUCTRPERM
Don’t worry, this is a common setup issue and it’s easy to fix! It means you need to grant users permission to access the GPU’s performance counters.
What you need to do is to add a new line in the /etc/modprobe.d/nvidia.conf with the following content:
options nvidia NVreg_RestrictProfilingToAdminUsers=0
Then, you need to reboot the machine. Now you should be able to run the ncu command and profiler our CUDA programs.
A Note for Fedora and Similar Systems
Following the NVIDIA guidelines, in some Linux distributions like Fedora, you might need to rebuild the initrd. If the reboot alone doesn’t do the trick, you’ll need to rebuild it.
dracut --regenerate-all -f