New firewire stack makes more FFADO XRUNs than old firewire stack.

[Takashi Sakamoto]

I have a firewire audio device, M-Audio Firewire Solo. It works fine in Lucid but not so good in Marveric because of much FFADO XRUNs in jackd2.

My IEEE 1394 chipset is below,
FireWire (IEEE 1394): Ricoh Co Ltd R5C832 IEEE 1394 Controller (rev 04)

$ dpkg -l | grep ffado
ii ffado-dbus-server 2.0.1+svn1856-1ubuntu1 FFADO D-Bus server
ii ffado-mixer-qt4 2.0.1+svn1856-1ubuntu1 FFADO D-Bus mixer applets (QT4)
ii ffado-tools 2.0.1+svn1856-1ubuntu1 FFADO debugging and firmware tools
ii libffado2 2.0.1+svn1856-1ubuntu1 FFADO API

At first, the kernel modules for this device is "New Firewire Stack" (so-called by FFADO developer), firewire_ohci, firewire_core and crc_itu_t. Then I get much FFADO XRuns,

Secondly I use "Old Firewire Stack", ohci1394, raw1394, ieee1394 with the commands of rmmod and modprobe, these modules are standard in Lucid. Then I got a few FFADO XRUNs.

In both ways, I play the same music in the same sequencer.

In detail, please refer to the logs of "ffado-diag" and "jackd -v" I'LL attach. The "_old" means the old firewire stack and the "_new" means new one.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: libffado2 2.0.1+svn1856-1ubuntu1
ProcVersionSignature: Ubuntu 2.6.35-22.33-generic 2.6.35.4
Uname: Linux 2.6.35-22-generic i686
Architecture: i386
Date: Tue Sep 28 13:22:50 2010
InstallationMedia: Ubuntu-Studio 10.10 "Maverick Meerkat" - Beta i386 (20100902.1)
ProcEnviron:
 LANG=ja_JP.utf8
 SHELL=/bin/bash
SourcePackage: libffado

[Stefan Richter (stefan-r-ubz)]

If I understand the jackd logs correctly, jackd is running in the common SCHED_OTHER scheduling class rather than the SCHED_FIFO class. Have a look at http://jackaudio.org/linux_rt_config regarding the configuration steps to grant your account access to realtime scheduling classes. This is generally important for jackd in order to lower the likelihood of audio buffer underruns/ overruns.

[Takashi Sakamoto (mocchi)]

Stefan,

Now I use 11.04 and get enough work.
Thanks,

[Pander (pander)]

From FFADO maintainer:

   Bug: More xruns under new Firewire kernel stack compared to the old stack.

   Suggestion:
       The final comment in this bug report suggests that an upgrade to
       Ubuntu 11.04 resolved the problem. The bug should therefore be
       closed.