Ulimit... What are the consequences of messing with it?

General Discussion
1

In the README.md I note:

When using jacktrip with the JACK Audio Connection Kit (or Pipewire), ensure that your user account has permission to schedule realtime processes.
ulimit -r should return a value greater than 40.

When I check, I see:

$ ulimit -r
0

The Bash manual suggests ulimit -r 41 but:

$ ulimit -r 41
bash: ulimit: real-time priority: cannot modify limit: Operation not permitted
$ sudo ulimit -r 41
sudo: ulimit: command not found

Eventually, with a bit of poking around I found I could do something like:

sudo echo "username hard rtprio 41" >> /etc/security/limits.conf

But I’m not sure how dangerous that might be. Any caveats?

2

It’s very important to run both Jack and JackTrip with high real-time priority. They’ll both try to do this on their own, but when you are running on Linux, you need to make sure they have permission to do it.

What happens if you don’t? It depends. If you have really beefy computer with plenty of CPU to go around, it will probably make no difference. If however you have other applications running and are pushing say > 30%, you may start to “hear” it in terms of static, pops, clicks, etc. I’ve noticed just dragging a window around can create a sound when things are not tuned properly.

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