[linux-audio-user] xruns - FC2/Planet(custom) vs. Gentoo(custom)

Lee Revell rlrevell at joe-job.com
Sun Oct 3 20:28:19 EDT 2004


On Sun, 2004-10-03 at 19:48, Fernando Pablo Lopez-Lezcano wrote:
> On Sun, 2004-10-03 at 15:54, Mark Knecht wrote:
> > <SNIP>
> > > Yep.
> > > 
> > > If you've allready checked the threading library versions (someone
> > > allready metioned that) I would look at filesystems and mount options.
> > > 
> > > X drivers are a possbilitlity, but most of the other drivers should be the
> > > same as youre running the same kernel, so it reduces the number of
> > > variables a lot.
> > > 
> > > - Steve
> > > 
> > 
> > SO I guess it could also be a problem of some sort with the Gentoo
> > ebuilds for Jack or Jack apps. Another possibility I almost called
> > attention to earlier is this little bit of text when Jack starts up:
> > (It was in the initial email)
> > 
> > <SNIP>
> > 08:10:43.247 /usr/bin/jackd -R -dalsa -dhw:0 -r44100 -p64 -n2
> > 08:10:43.252 JACK was started with PID=14453 (0x3875).
> > cannot write to jackstart sync pipe 4 (Bad file descriptor)
> > jackd: wait for startup process exit failed
> > jackd 0.98.1
> > Copyright 2001-2003 Paul Davis and others.
> > <SNIP>
> > 
> > What is a 'jackstart sync pipe 4'? Could this error be part of the
> > problem? I have to boot back to FC2 to see if it's there, but from
> > memory I thought maybe it wasn't...
> 
> Yes, that may be the problem, my guess would be that jack may not be
> getting realtime priority. I would check that all processes involved
> (jackd and the clients as well) are really running SCHED_FIFO (ie: with
> realtime priority). 
> 

As a test, you could try building JACK from source (IOW, bypassing the
Gentoo ebuild process) and see if the problem persists.  I agree with
Fernando that this looks like a problem with the Gentoo ebuild.  I have
never seen that 'jackstart sync' message before.  On 2.6 jackstart is
completely unnecessary.  It looks like on Gentoo jackd might be a
wrapper script that exec's jackstart or something, which fails because
it can't get allcaps.  Just a guess, I don't have access to a Gentoo
system.

The problem is that until recently, it was a safe assumption that anyone
using JACK would be on 2.4.  Audio on 2.6 is a pretty recent
development, I would not be surprised if more bugs like this turn up.

Lee



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