Subject: Re: [linux-audio-user] xruns - FC2/Planet(custom) vs. Gentoo(custom)
From: Fernando Pablo Lopez-Lezcano (nando_AT_ccrma.stanford.edu)
Date: Mon Oct 04 2004 - 02:48:43 EEST
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).
The program to use is chrt (/usr/bin/chrt, part of the schedutils
package, don't know where you would find it on gentoo).
/usr/bin/chrt -p PID
(where PID is the process id of the process you want to check)
A ps -auxw will list all processes, but if you are running nptl it will
not list all threads (I think there is also an option for ps to show
them, can't remember it now), you can find the pid of all the threads
for a given process in /proc/PID/task/*
-- Fernando
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