[mythtv-users] How MANY backend threads!?!?!?

[Daniel Kristjansson]

On Wed, 2010-10-13 at 22:28 +0100, Steve Smith wrote:
> With 0.23 I'm getting much higher CPU usage when recording (avg 30-40%
> on my P3 900Mhz, previously about 10-20% on 0.21).
> This means I can't do "chase play" which I used to be able to do.
> 
> I've done a ps -eLf and can see 32 yes 32 backend threads....
> 
> Is this normal? Can it be reduced to get the CPU usage down a bit?

The number of backend threads has no direct relation to the number
of CPU usage. Over the last few versions we've reduced standby power
usage by getting rid of busy loops which has caused us to need more
threads. We've also introduced features like UPnP which launches
several threads that wait patiently for someone to connect to a
socket.

I don't know a lot about your setup so this is a stab in the dark..
do you record from a framegrabber and use MPEG-4 compression? For
a while we had accidentally ignored some compression settings that
were configurable in the recording profiles. When we started
respecting those features CPU usage shot up. The fix is simply to
disable these compression settings in the recording profiles you
use. Those features weren't being used before so you won't there
will be no loss in quality. I'm sorry I can't be more precise, 0.21
was a long time ago, and maybe this isn't even the problem you are
seeing. But if it is applicable you can search this list.

BTW You will not want to upgrade that machine past 0.23. Starting with
0.24 we generate previews on the master backend, so that machine needs
to be many times more powerful than it had to be in the past.

-- Daniel