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diff --git a/doc/user.xml b/doc/user.xml index f66f6e397..e30b667ca 100644 --- a/doc/user.xml +++ b/doc/user.xml @@ -1025,6 +1025,58 @@ database { plugin). </para> </section> + + <section id="realtime"> + <title>Real-Time Scheduling</title> + + <para> + On Linux, <application>MPD</application> attempts to configure + <ulink + url="https://en.wikipedia.org/wiki/Real-time_computing">real-time + scheduling</ulink> for some threads that benefit from it. + </para> + + <para> + This is only possible you allow <application>MPD</application> + to do it. This privilege is controlled by + <varname>RLIMIT_RTPRIO</varname> + <varname>RLIMIT_RTTIME</varname>. You can configure this + privilege with <command>ulimit</command> before launching + <application>MPD</application>: + </para> + + <programlisting>ulimit -HS -r 50; mpd</programlisting> + + <para> + Or you can use the <command>prlimit</command> program from the + <application>util-linux</application> package: + </para> + + <programlisting>prlimit --rtprio=50 --rttime=unlimited mpd</programlisting> + + <para> + The <application>systemd</application> service file shipped + with <application>MPD</application> comes with this setting. + </para> + + <para> + This works only if the Linux kernel was compiled with + <varname>CONFIG_RT_GROUP_SCHED</varname> disabled. Use the + following command to check this option for your current + kernel: + </para> + + <programlisting>zgrep ^CONFIG_RT_GROUP_SCHED /proc/config.gz</programlisting> + + <note> + <para> + 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. + </para> + </note> + </section> </chapter> <chapter id="use"> |