> > IIRC, Ubuntu "RT" kernel is not actually Real Time (i.e. with Ingo > patches), just a "desktop RT" which is not very useful for audio and > certainly not enough for JACK apps of any heft. >
Where are you getting this info from? This is not what I have read, but maybe I am missing something somewhere. I thought that the Ubuntu kernel packagers recently switched to using full realtime preemption... I find this in the package description of linux-image-2.6.22-14-rt : Ingo Molnar's full real time preemption patch (2.6.22.1-rt9) Here is the output of uname -a: Linux pal 2.6.22-14-rt #1 SMP PREEMPT RT Tue Feb 12 09:57:10 UTC 2008 i686 GNU/Linux .. and here are the kernel settings from cat /boot/config-2.6.22-14-rt | grep PREEMPT # CONFIG_PREEMPT_NONE is not set # CONFIG_PREEMPT_VOLUNTARY is not set # CONFIG_PREEMPT_DESKTOP is not set CONFIG_PREEMPT_RT=y CONFIG_PREEMPT=y CONFIG_PREEMPT_SOFTIRQS=y CONFIG_PREEMPT_HARDIRQS=y CONFIG_PREEMPT_BKL=y CONFIG_PREEMPT_RCU=y # CONFIG_DEBUG_PREEMPT is not set # CONFIG_CRITICAL_PREEMPT_TIMING is not set Looks realtime to me.. also the latency is really low (5-10ms conservatively), much lower than I have experienced on other OS's, with or without realtime. But, if you know something I don't... I have open ears. Ubuntu runs so nicely on a laptop though... would hate to switch after finding such an easy-to-operate linux distribution because pd and only pd doesn't like jack in realtime. regards, rich > The "pops/clicks" phenomenon you are noticing that gets resolved by > starting or killing another JACK app, is something I've experienced before. > It happens when some app gets an Xrun or otherwise can't process audio in > time. From that point forward it "clicks" and, in my experience, distorts as > well with some bitcrushing-style aliasing distortion. When you start or stop > any JACK app, the entire JACK graph structure gets re-ordered (this isn't > true with jackdmp, just with single-processor JACK), and that causes the > misbehaving app to "start from scratch" somewhat and get its audio organized > properly. > > I'd suggest 64Studio, Musix, Pure::Dyne, or some other distro that has the > really serious RT set up with the Ingo patches. With one of those distros, > everything should run very well on a machine of any decent heft. > > -ken >
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