[mythtv-users] Need help troubleshooting cause of DMA Timeouts

Craig Huff huffcslists at gmail.com
Tue Aug 23 23:48:32 UTC 2011


I had a stable BE/FE running MythBuntu 10.04 on a single core Athlon
64 cpu and foolishly (or so it seems) decided to upgrade to a
dual-core Athlon II cpu to enable more concurrent processing.  I can't
see any reason why this would cause the problem I'm having, but
nothing else has changed.

Since then I randomly get system lockups where nothing can reach the
backend process and/or the mysql service and yet the mouse and
keyboard still get response, more promptly for the mouse, but still...
 The only recourse seems to be to restart an undetermined number of
processes or treat it like windoze and reboot.  Naturally the WAF is a
little better using the sledgehammer approach ;-)

When it acted up last night, these snippets are the closest I could
find to a smoking gun:

/var/log/syslog:
...
Aug 22 21:35:01 penguin CRON[14069]: (mythtv) CMD (echo "`date +%r`:
`sensors -f | grep 'CPU Temp'`" >> /var/tmp/temperature.log 2>&1)
Aug 22 21:35:59 penguin kernel: [11811.996029] ivtv3: DMA TIMEOUT 00000001 2
Aug 22 21:35:59 penguin kernel: [11812.296025] ivtv3: DMA TIMEOUT 00000001 0
Aug 22 21:36:00 penguin kernel: [11812.596027] ivtv3: DMA TIMEOUT 00000001 2
Aug 22 21:36:02 penguin kernel: [11815.164029] ivtv3: DMA TIMEOUT 00000001 2
...

and /var/log/kern:
Aug 22 18:20:45 penguin kernel: [   97.684037] Clocksource tsc
unstable (delta = -148975716 ns)
Aug 22 21:35:59 penguin kernel: [11811.996029] ivtv3: DMA TIMEOUT 00000001 2
Aug 22 21:35:59 penguin kernel: [11812.296025] ivtv3: DMA TIMEOUT 00000001 0
Aug 22 21:36:00 penguin kernel: [11812.596027] ivtv3: DMA TIMEOUT 00000001 2
Aug 22 21:36:02 penguin kernel: [11815.164029] ivtv3: DMA TIMEOUT 00000001 2

This latest flub, as usual was after a random period of minutes to
hours after boot-up with no discernible pattern leading up to the
lockup.  Also, the most recent recording start was over 35 minutes
before the problem surfaced, and should have continued to the top of
the next hour.  Can anyone suggest causes or things to look at?

FWIW, I normally start commflagging immediately, but just recently
changed it to wait until after the recording had finished -- didn't
help.  Also, I have the commflag job "de-niced" to minimize I/O
loading with a lowered ionice setting.  I can dig up the command
string if someone thinks it might be a clue, but it has been that way
for years.

TIA,
Craig.


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