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

Stuart Larson halcyon at obfus.com
Mon Feb 27 20:56:23 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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Sorry, it was a badly formatted email.  I'm running ReiserFS on the LVM.

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