[linux-audio-user] 2x RME Multifaces, ALSA, JACK & Ardour -> XRUNS?

Hello LAU, I've been battling with this problem for about a week now, have searched all over the place and have still not found a solution. I'm hoping somebody on this list can help me out... Hardware is as follows: Dell PE1800 Dual 2.8GHz EM64T w/1GB RAM PERC4/SC RAID5 (configured with write-back caching - bonnie++ reports 50MB/s block writes) 2x RME Multifaces (configured with Word clock sync/ADAT fiber cable for sync) OS Specifics: Gentoo Linux (fairly conservative CFLAGS=" -march=k8 -O3 -pipe") Kernel version 2.6.12 XFS / filesystem Goal: Record 16 tracks using the 8 analogue inputs of the each of the two cards simultaneously in ardour without any XRUNs. Symptoms: qjackctl reports hundreds of XRUNs when the system is sitting idle with nothing more than the window manager (KDE 3.4.1) and Jack running. I can get ardour to record if I tell it to ignore XRUNs, but that's obviously not what I want. Strange thing is that jackd -v doesn't always report XRUNs that ardour and qjackctl seem to complain about. The different things I've tried: 1) Ingo Molnar's realtime-preempt-2.6.12-final-V0.7.51-06 patch (could only get it to compile with full preempt on x86_64). I've tried this as well as the standard Gentoo sources kernel without the patch - no apparent difference. 2) With and without realtime-lsm (I tried using rtlimits too, but I'm not sure that I had it setup correctly). The problem still occurs even if I run everything as root - so I don't think it's a permissions/capabilities problem. I've also tried various chrt -f priority levels for everything, including using chrt -f -p 99 on the sound card IRQs. Strange thing is that half of the KDE stuff (like kicker) also shows up with PR = RT in top, but chrt reports SCHED_OTHER, priority 0 for all of these. 3) Synchronising the two multifaces with Word clock (at 48kHz) as well as ADAT in (at both 48 and 96kHz). The problem is worse at 96kHz but it happens at 48kHz too - ultimately I would like to run a 96kHz configuration, but I thought I'd try 48 too. 4) Various jackd settings (including various -R -P ? optional as well as all -p options). Problem still occurs with -p 8192. 5) Various configurations in /etc/asound.conf for binding the two cards together, but I must admit I don't really know what I'm doing here and everything has been pieced together from examples on the web. I've attached the current version of the file which has options for the 48 and 96kHz configurations of the multifaces. I've also tried leaving the ADAT and SPDIF channels out of the configuration, since I'm only interested in the analogue inputs. 6) Tried jack and ardour without KDE running (under TWM) - no funny processes with RT Priority in top, but problem still persists. I suspect it may only be a bug in top tho', since chrt still shows sensible stuff. 7) I couldn't install Gentoo's media-sound/alsa-driver package against the Ingo Molnar patched sources, but the problem is still there when I compile alsa-driver separately (version 1.0.8 and 1.0.9b) using the standard gentoo kernel sources. 8) With and without NPTL (I had NTPL enabled glibc installed until I read about possible problems with it). I tried the LD_ASSUME_KERNEL work around first and eventually even recompiled glibc with USE=-nptl. 9) Tried taking qjackctl out of the loop - running jackd manually - same problem with ardour. 10) Recording all 18 channels with only one of the two multifaces configured (tested both of them) works fine in all of the above configurations that I tried it with - including without Ingo's RT patches. I'm now totally lost. I've eliminated everything I can think of and don't know what to try next. Any help would be greatly appreciated. Thanks. - Edwin -- #include http://www.peer.co.za/~espeer/disclaimer.html