On Wed, May 21, 2008 at 02:23:20PM -0700, Rich E wrote: > > > > 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
My info is from having installed Ubuntu and used it... but that was a few years ago. Glad they're using Ingo's patches now. > 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. Nope, you got real-time there, for sure. I was wrong then. > 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. > Dunno. You're playing Xrun whack-a-mole. Done that; it's not fun. Here's what I did to RT-ify my system (on Debian, but Ubuntu is based on it): http://www.restivo.org/blog/archives/preparing-a-debian-etch-system-for-audio-use Also, I expect you know to use chrt to give the IRQ of your audio interface top priority, higher than JACK and any other process. That's a crucial step. If I omit that, then I get clicks and pops too, which is why I wrote a script to do it automatically. You could also install and configure the "rtirq" package, which works great too. -ken _______________________________________________ [email protected] mailing list UNSUBSCRIBE and account-management -> http://lists.puredata.info/listinfo/pd-list
