On Linux, MPD attempts to configure real-time scheduling for some threads that benefit from it.
This is only possible you allow MPD
to do it. This privilege is controlled by
RLIMIT_RTTIME. You can configure this
privilege with ulimit before launching
ulimit -HS -r 50; mpd
Or you can use the prlimit program from the util-linux package:
prlimit --rtprio=50 --rttime=unlimited mpd
The systemd service file shipped with MPD comes with this setting.
This works only if the Linux kernel was compiled with
CONFIG_RT_GROUP_SCHED disabled. Use the
following command to check this option for your current
zgrep ^CONFIG_RT_GROUP_SCHED /proc/config.gz
There is a rumor that real-time scheduling improves audio quality. That is not true. All it does is reduce the probability of skipping (audio buffer xruns) when the computer is under heavy load.