[linux-audio-user] Tracking down overruns

[Benji Flaming]

Greetings all!  I am attempting to initiate a long unattended 2-channel
audio recording - perhaps lasting for an hour or two - but I am prevented
from doing so by periodic overruns which occur at regular intervals.  This
interval changes according to my system configuration.  Currently, I
consistently get an overrun about 20 minutes after I start recording.

My system is an AMD Athlon XP 1700+ with 256mb DDR266 memory.  Video card is
an ATI Radeon 7500/64mb.  Sound card is an M-Audio Audiophile 2496.  I'm
running Slackware 9.0.  My kernel version is 2.6.test5.  Prior to this
kernel I was using 2.4.21 with low-latency and preemptible kernel patches -
with exactly the same overrun issue.  I'm using jackd version 0.79.2,
Ardour/GTK 0.378.0, and libardour 0.686.0 (all built from CVS source a few
weeks ago.)  I'm starting jackd with the command:

jackd -v -a -R -d alsa -d ice1712 -r 44100 -p 2048

I don't want to clog everyone's mailbox with an even bigger message, so I've
posted a bit of additional info online.

Results from running latancytest0.42-png:
http://www.comevisit.com/NorthernSunrise/latency/3x256.html
http://www.comevisit.com/NorthernSunrise/latency/test2/3x256.html

My .config file from my most recent 2.6.test5 kernel build:
http://www.comevisit.com/NorthernSunrise/latency/.config

My jack, and ardour version numbers, and hdparm info for hda and hdb:
http://www.comevisit.com/NorthernSunrise/latency/configuration

I can see from the latency tests that *something* is causing spikes,
particularly during disk write, but I'm not sure how to determine precisely
what it is.  Is there any way to obtain a snapshot of processor usage at the
exact moment of an overrun?  Any help or advice (or reminders about what
info I've neglected to give) would be very much appreciated!

|)
|)enji

Benjamin Flaming
--------------------
"The trouble with computers, of course, is that they're very sophisticated
idiots."