I noticed that a
pulseaudio process on my Gentoo Linux machine has the nice level of -11. But I don't know how it has gained such a high priority regardless of being owned by a normal user.
I know a non-root user can launch a program only with a lower priority than 0 with the
nice command, and it says "Permission denied" if we try to give a process a higher priority than 0.
pulseaudio process is owned by me (a non-root user), I think it cannot get such a high priority without any special treatment.
So, my question is what "treatment" does enable
pulseaudio to have a low niceness value.