Subject: Re: [Jackit-devel] Re: [linux-audio-dev] Re: [Jackit-devel] 2.4.20Â + lowlat +preempt + alsa + jack = dead computer
From: Fernando Pablo Lopez-Lezcano (nando_AT_ccrma.Stanford.EDU)
Date: Tue Dec 31 2002 - 05:17:45 EET
> > qjackconnect. I'm currently trying to see if I can start the stuff from
> > the text console so that I can try to catch some register dumps through
> > the sysrq magic key...
>
> I don't have the time now to analyze the results but it would seem the
> problem is freqtweak in combination with jackd. When the system freezes
> after starting stuff from a text console, <alt>sysrq-p prints
> information about the current registers and the printout of repeated
> dumps only shows the jackd and freqtweak processes over and over again.
>
> Somehow they must be deadlocking.
Good news (apparently - most probably the machine I'm testing on will
freeze while I'm typing this message :-)
The problem with 2.4.20 appears to have been ext3. I finally got a trace
of the deadlocked processes through the sysrq key (after retyping lots
of boring numbers from the screen) and ksymoops is pointing to something
stuck in ext3. With that clue I went to the ext3 site:
http://www.zip.com.au/~akpm/linux/ext3/
And sure enough there were patches for 2.4.20 and one of them was a
deadlock condition. I applied them, rebuilt the kernel and the machine
appears to be _finally_ happy (I'm still typing and it has not
deadlocked).
This is with 2.4.20 + lowlat + preempt + o(1) scheduler (most of Con
Koliva's patchset) plus some extras, running latest alsa cvs plus jack
and a bunch of jack clients.
Well, it did not freeze after all... let's see if I can get to the send
message button before it does :-)
-- Fernando
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