[LAU] Are RT-patches needed anymore? (Was Re: >= 2.6.27 RT ETA?)

[Ken Restivo]

On Tue, Jan 27, 2009 at 06:16:33PM +0100, Peder Hedlund wrote:
> Quoting Svend-Erik Kj?r Madsen <sv-e at sv-e.dk>:
> 
> > On tir, 2009-01-27 at 15:03 +0100, Cassiel wrote:
> >
> >>
> >> 5.3ms latencies: If you can't sense it... you don't need it
> > I just ran a few test with a keyboard playing both the keyboard's
> > soundmodule and through midi and Qsynth, and I must admit that latency
> > was down to 1.3 ms before the audible time differece disapeard.
> 
> Ok, I have to admit to lying; I only managed to go down to 5.8 ms  
> (128/44100/2).
> But, then again, I'm running a generic vendor kernel (2.6.25.11) on a  
> seven years old CPU. I'd imagine a modern CPU being able to go lower,  
> so my question remains:
> Has anyone with a modern PC tried to go low-latency with a non-patched kernel?
> 

My requirements are very specific: I play live with other musicians, via MIDI, and it's funk music, and I play bass through my Linux laptop. Therefore, I have to be locked in with the drummers. When I hit the 1, it has to be right on top of the kick drum. I also use a lot of softsynths, and I'm playing live, so Xruns are unacceptable. Consistently LOW latency with no Xruns and CPU-intensive softsynths are very important to me.

That said, my current setup is a 2.33Ghz Core 2 Duo with a RT kernel and JACK set to -r 44100 -P 128 -n 3, using a USB soundcard and USB MIDI keyboard. I haven't calculated out what latency that is in milliseconds, but whatever it is, so far it works fine for me. It feels like I'm playing an actual instrument, not a sluggish computer.

-ken