[mythtvnz] Mythbackend crashes

[Wade Maxfield]

>Has anyone had any luck tracing the cause of the recent DVB issues that were
>widely reported.
>
>Is anyone running a DVB card and has not experienced crashes over the last
>week, if so could you perhaps post your setups and versions so we can
>perhaps find some commonality.
>
>I'm running a skystar technisat with knoppmyth R5C7 with IVTV upgraded to
>4.4.
>Mythbackend consumes 100% system resources within about 30 minutes of
>opening the DVB card.
>Tonnes of free disk space and repaired and checked MYSQL tables.
>Nothing odd coming up in any system or myth logs.
>
>My conclusion based on the fact that many people are having the same problem
>running various different versions of myth is that either something has
>changed in the DVB signal or there are too many errors or problems with the
>signal and either the card or mythbackend isn't coping with it.
>
>Regards
>Toby Mills
>www.np.co.nz
>

No luck tracing, but my machine hasn't actually crashed.  I've just 
noticed tremendously slow downs, towards the end of recording, and 
this was verified watching top at the time.
Machine running FC5 x86_64 (kernel 2.6.17-1.2174), ivtv 0.7, 2GB RAM, 
2GB SWAP, combined backend/frontend but only acting as a backend at 
the time.

I don't know all the intricacies of top and what all the data means but:


3.5hr program on Sunday night
at start of recording Free Mem was around 1.6G and Free swap was 2G, 
by the end of the recording Free Mem and Free Swap were both less 
than 16M.  Right at the end of the recording, before commflagging 
started, the wa% was sitting around 80-95%.  mythbackend CPU was 
around 4% for the whole of the recording. Normally it's less than 1% 
when using the PVR150.

2 x 1hr programs back to back on Monday night. At the end of the 
first program Free Mem was less than 16M and Free SWAP was around 
700M, about 3 minutes after the recording finished I got about 600M 
of swap back.  By the end of the second recording Free SWAP was back 
down to 16M.  A couple of minutes later it gave some back (900M or so)


So for some reason mythbackend just keeps grabbing memory and not 
giving it all back.  I'm guessing I haven't crashed yet, since I have 
a bit more headroom.

One thing I have noticed in my backend log is towards the end of the 
recording I have lots of messages like
[mpeg2video @ 0x31fac5c150]invalid mb type in I Frame at 1 31
[mpeg2video @ 0x31fac5c150]ac-tex damaged at 0 32
[mpeg2video @ 0x31fac5c150]ac-tex damaged at 0 33
[mpeg2video @ 0x31fac5c150]ac-tex damaged at 0 34

which from looking in the gossamer archives seems to suggest either 
weak signal strength or PCI timing issues/conflicts between hard 
drive controller and DVB card PCI bridge chip.  The messages I saw 
regarding the signal strength all said that their TV/STB had no 
problem, just their DVB card/myth box.  Which is similar to my 
experience.  So I think it's got to be the signal.  Maybe it'll all 
come right when the switch to Optus D1 happens (anyone have a 
guesstimate?)

In the mean time I've switched the priority of my DVB card to be 
lower than my PVR150

  - Wade