It depends the engine, but reading this analysis:
i would say that the performance reduction is about 8-10%, what is not too much.
But if you take a look to the latency metrics, you can see a very interesting thing:
- maximum kernel latency for “standard” kernel: 300us
- maximum kernel latency for “RT” kernel: 90us
what makes no difference for “our” audio use-case, given that we are running jackd at 5-10ms of latency, the little difference on kernel latency only gives a marginal advantage on reducing jitter, but, from my point of view, not enough for justifying the 10% loss on performance.
I’ve read and thought quite a bit about this subject and always reach the same conclusion:
We don’t need a RT kernel on zynthian. Simply it’s not the right use-case for that.
A RT-kernel only is needed when your application has strict latency requirements of <1ms.
I other words, by using a RT-kernel, you won’t avoid or reduce the XRuns, and you won’t get a lower latency with jackd. You only will get a slighty better jitter and 10% less CPU power.
Regards,