[linux-audio-user] xrun madness - test results (long)

[Jack O'Quin]

Good report, thanks for all the info.

Joel White <cv223 at comcast.net> writes:

> With 2.6.9 - In Duplex mode, xruns occur at a rate of scores per min
> of recording on *either* drive.  Kernel latency trace indicates that
> the max kernel latencies were around 200 - 400 usec.  Xruns are
> eliminated when Jack is set to Capture only.


> 3.  It seems that there is some kind of interaction between Ardour,
> the kernel, and the disk system.  The fact that xrun behavior is so
> different between the two kernels (xruns on the IDE drive with 2.6.9,
> but not 2.4.23)  suggests something is up with the kernel.  The
> latency_trace on 2.6.9 does not report that the kernel latency is the
> problem, but it is clearly something going on with this kernel.  It is
> certainly possible that I have something misconfigured (Lee Revell
> checked out my .config, so at least that seems ok).  I can send more
> info to anyone who may be able to help.

I recently built 2.6.9 to test the latest realtime-lsm LKML patch.
The patch worked, but realtime performance was horrible on my system,
especially compared to 2.6.8.1.  I ran JACK in Duplex mode with ardour
and jamin.  Next, I built 2.6.9-mm1, and things are working pretty
well.

So, despite not having done a careful test like yours, I think there
is a latency problem with 2.6.9.  I'd be very interested to see what
happens if you run your test on 2.6.9-mm1.  The kernel developers
probably would, too.
-- 
  joq