RealtimeKit and the audio problem

> you say kill disk I/O and network I/O

> what if you are using one of those for your audio? how is the system supposed to know?

Probably by PID number. I was under the impression that the Linux I/O scedualer was capable of prioritizing different things.

The disk access can almost always be delayed because of the nature of cache in ram. A system can't prioritize incomming network packets becuase you need to analyze the packet first to determine weither or not it's priority, but processes can be give priority on network access.

This is all stuff that is already in the kernel.

> it's a very different thing to say that the system should prioritize your audio over everything else than to say that the system shouldn't have 500ms pauses. the latter is something that everyone can agree to, the former is not.

Ya... Its more complicated then you think here, I think.

Very low-latency = low performance. A system that has very good low-latency behavior tends to be inefficient. This means reduced performance for web servers, file servers, database servers, encryption, etc etc.

So it's certainly not something everybody can agree on. So it has to be tunable. Which is the point behind having a configurable system were you can assign "realtime" performance to key processes at the detriment for the rest of the system.

Audio is just one of the many times you need to have good "realtime" performance.

Any time your having a computer interacting with the real world.. You can't pause real-life. You can't put events in a buffer and schedual things so that you can have good performance.. many times the computer needs to react to events outside of it's control in a timely manner.

Robot controls, scientific instrumentation, vehicle navigation systems, vehicle control systems, cell phones, VoIP devices, wallstreet stuff blah blah blah.

It'll be nearly impossible to make Linux ever perform "hard realtime" but certainly things can be improved to the point were the utility of the vanilla Linux kernel can be increased massively.