Comment by viraptor
> Is there any reason to not just have RT on by default?
It's a latency vs throughput trade-off usually. Ideally you'd want both to improve, but the more you switch between the processes, the more time you waste on busywork and cache invalidation rather than what the processes want to achieve. For example if RT wants to guarantee that your audio is more in sync, you're going to switch from your app to the audio system more often.
That's a bit of a red-herring though, as the audio system will only preempt other processes if it's configured for very small buffers and given real-time permissions. A server's audio subsystem won't preempt actual work because a server won't _have_ an audio subsystem running, let alone be configured for sub-millisecond latency.
The real trade-off is the overhead required to make all kernel operations potentially safe WRT maximum wait times.