[linux-audio-user] Tracking down overruns

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Subject: [linux-audio-user] Tracking down overruns
From: Benji Flaming (lau_AT_solobanjo.com)
Date: Sat Sep 13 2003 - 23:16:17 EEST


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."


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