[vdr] Strange CPU usage cycling after user inactivity

Brendon Higgins blhiggins at gmail.com
Sun Jul 1 04:47:38 CEST 2007


Hi there,

I'm looking for help solving a strange issue I'm having with my vdr system. 
It's an AMD64 Debian box, kernel 2.6.18, running vdr 1.4.7, input from a 
DViCO FusionHDTV DVB-T Plus card, output through a dxr3 card (actually a 
Hollywood+).

When I'm watching TV everything is fine. After I stop watching and leave vdr 
on its own for a while, weird things start to happen. After a while (I 
suspect it's when vdr thinks the user inactivity period has expired) vdr 
starts into some weird cycle. For a minute or two vdr runs using ~1/4 of my 
CPU, apparently busy with IO. After that it returns to normal, using usually 
a few percent of the CPU. But then after a few more minutes it peaks up to 
25% again, and the cycle continues.

I've narrowed it down to the following messages in syslog. This first message 
appears at the same time as the weird CPU usage starts:

Jun 30 21:12:46 phi kernel: cx88[0]/2: cx8802_timeout
Jun 30 21:12:55 phi vdr: [3452] frontend 0 timed out while tuning to channel 
0, tp 536
Jun 30 21:13:16 phi vdr: [3452] frontend 0 timed out while tuning to channel 
0, tp 543
Jun 30 21:13:37 phi vdr: [3452] frontend 0 timed out while tuning to channel 
0, tp 564
Jun 30 21:13:58 phi vdr: [3452] frontend 0 timed out while tuning to channel 
0, tp 571

On (or not long after) the fourth vdr message (always comes in fours) things 
settle back to normal, until the next cx8802_timeout, two minutes later 
(accurate to within a few seconds, actually).

Now, this needs to be an always-on machine, and I want it to use as least 
power (electricity, and thus, CPU) as possible, so it's annoying me that it 
seems to be doing this IO processing seemingly unnecessarily.

It's been doing this a while, probably a few months. I think it started some 
minor revision ago, but I can't be certain. I'm a bit confused that it's 
trying to access channel 0, since AFAICT there is *no* channel 0.

Help?

Thanks,
Brendon



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