Arch Linux

Description:
To enable realtime scheduling support for gnome-shell on Wayland it isn't necessary to set CAP_SYS_NICE on /usr/bin/mutter. It suffices to do that for /usr/bin/gnome-shell.

Additional info:
* package version(s)
* config and/or log files etc.
* link to upstream bug report, if any

Steps to reproduce:
Enable realtime scheduling:
$ gsettings set org.gnome.mutter experimental-features "['rt-scheduler']"
Remove CAP_SYS_NICE from mutter binary:
$ sudo setcap CAP_SYS_NICE=-ep usr/bin/mutter
Reboot/Re-login (using Alt+F2 doesn't work on Wayland)
Check realtime scheduling support:
$ ps -C gnome-shell -Lo pid,cls,comm,command
1179 RR gnome-shell /usr/bin/gnome-shell
1179 TS gmain /usr/bin/gnome-shell
1179 TS gdbus /usr/bin/gnome-shell
1179 TS dconf worker /usr/bin/gnome-shell
1179 IDL gnome-s:disk$0 /usr/bin/gnome-shell
1179 TS JS Helper /usr/bin/gnome-shell
1179 TS JS Helper /usr/bin/gnome-shell

I suppose the relevant dconf key being named org.gnome.mutter causes confusion in this context.
In any case, this doesn't keep gnome-shell from being able to run with realtime scheduling support, but it doesn't seem strictly necessary to set CAP_SYS_NICE for mutter.