[mythtv-users] Mythbackend taking 50% CPU w/PVR150 or 250 when recording

Michael T. Dean mtdean at thirdcontact.com
Mon Feb 27 20:39:29 UTC 2006


On 02/27/2006 11:30 AM, Stuart Larson wrote:
> Hi all,
>   First off, system info:  Myth from 0.19-fixes branch, checked out from
> 2/24/06.  Running the backend on FC4, IVTV 4.2, and two PVR cards - one
> is a 150, the other a 250.  My storage dir is on a 4-disk LVM, formatted
> in ReiserFS.  PC is an AMD Sempron 3100, with 1GB of ram.  DMA is
> enabled on all disks.
>    I've had no problems with recording up until this weekend.  What I
> started seeing is when mythbackend is recording, it starts taking up
> around 50% CPU.  Normally I wouldn't think this would affect playback
> on the local frontend (they are on the same machine), but if either of
> the cards were recording, I'd start seeing skips and pauses,
> corresponding to mythbackend's CPU usage.  The actual recordings, onced
> finished, play back fine, it just appears that playback of other media
> (the entire box was slow) suffered because of mythbackend taking up so
> much CPU.  Before this, the highest I saw mythbackend take was around
> 10%.  If it's relevant, I'm recording at 480x480, around 3500 bitrate,
> and I have 1 GB reserved for files.
>   What I noticed (and from searching the lists, it looks like this was an
> issue brought up but not really resolved), was that this started
> happening when my storage space went under 10G available.  Once I
> cleaned up some old recordings and got more space available, mythbackend
> went back to using 3-10% CPU when recording...  I did check the
> mythbackend log, and I did not see anything out of the ordinary - no
> messages about expiring old programs.  I ran it on --verbose all (whoah
> lots of info!) and also did not see anything out of the ordinary.
>   Has anyone seen this issue before?  I was able to resolve this just by
> cleaning out old recordings, but I wonder if there's a setting I'm
> overlooking that would cause/fix this type of behavior.
>   
IIRC, XFS is known to behave poorly with a "nearly" full filesystem.  
What filesystem are you using?

Mike


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