[mythtv-users] High load, low CPU usage

Ray Olszewski ray at comarre.com
Fri Jul 11 17:02:13 EDT 2003


Most of your responses say the things they are about are OK. I'm skipping 
to the few that are worth more discission.

This report is really a bit of a poser from my PoV. I often see (here and 
in reports) problems of high CPU use, but not moderate CPU use together 
with a high load number. So my suggestions are kind of wild guesses ... I 
hope someone else with more insight than I have will jump in here.

At 09:33 PM 7/11/2003 +0100, Steve Hill wrote:
[...]
> > 6. A real longshot here -- is it possible that the bttv and the sound card
> > are using the same IRQ? Or that you have a sound card that has trouble 
> with
> > full-duplex, something that would show up only when simultaneously
> > recording and playing (e.g., "live'" TV)? This is pretty wild guessing, 
> though.
>
>The machine has 2 soundcards in - a Soundblaster Live (used for the input)
>and a VIA82Cxxx on the motherboard used for the output.  I've tried
>switching the output to the SBLive, which didn't affect the problem at
>all.
>Looking at the IRQ list, both soundcards are on IRQ 10 and the TV card and
>video card are both on IRQ11, so this could be the problem (I will reboot
>in a bit and see if I can convince the bios to move them all onto
>different IRQs).

WIth two sound cards involved, it would help to know how you have sound 
configured ... is the same card doing both recording capture and playback?

I've never seen 2 sound cards sharing an IRQ, so I would think it worth 
looking more closely at that.

Usually, video cards don't really use their IRQ, so it and the bttv card 
sharing an IRQ is not a prime suspect here.

> > 7. Some miscellaneous items: How much RAM is in the system? What gbuffers
> > setting do you use with the bttv driver? What sound modules (OSS? 
> ALSA?) ar
> > you using?
>
>256MB of RAM (possibly not quite enough, but according to top the kernel
>is using 100MB of it as cache).
>What's the gbuffers setting?  I've not come across that before.

gbuffers are the amount of memory that the kernel reserves for buffering 
input from the bttv card. The default is 2, each 1024 KB. The maximum 
allowable is 32, and people typically seem to use 8 or 16. Add the argument 
"gbuffers=8" (probably the best choice with only 256 MB RAM) to whatever 
line controls installation of the bttv driver (probably in 
/etc/modules.conf, though that's actually a bit dsitro specific).

>And I'm using the stock EMU10K drivers (I think that's OSS).

I think so too. You **might** be running into a duplex problem that 
switching to the ALSA drivers (with the OSS emulator)  would be helpful.





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