[mythtv-users] Mythbackend causing high load

Stuart Larson halcyon at obfus.com
Fri Jun 16 18:55:24 UTC 2006


Yeah - I don't see it too often, only when free space gets down to around
what Myth has set for reserve-free-space.  At this point playback is jerky
until I delete some old recordings (I do have it set up to expire old
programs when low on space).  I don't see anything in the logs to this
extent... running .19-fixes, svn from last weekend.

> Interesting, I'm using ReiserFS and I have about 20GB free on a 300gb
> partition. However its been like this for about a month now, and worked
> fine before last week.
>
>
> On Fri, 2006-06-16 at 12:58 -0500, Stuart Larson wrote:
>> I've seen this sort of behavior when recoding or transcoding (doesn't
>> seem
>> to make a difference which) when my free space on drive was close to
>> what
>> Myth is set to keep free - I have Myth set to keep 20G free, and when it
>> reached around 22-23G free, I started seeing this behavior (I'm running
>> reiserfs, so the xfs space-free thing shouldn't be an issue).  Not sure
>> if
>> it would be related...  The recordings did work fine (PVR-250), but
>> watching while recording doesn't work very well.
>>
>> > I'm seeing something very familiar, mythbackend uses about 100% CPU
>> > during a recording and though not always, I sometimes see IOBOUND
>> errors
>> > in the log. I have transcode/commflag jobs set to run after midnight
>> > each day, and no other processes are using CPU while mythbackend is
>> > hogging it all.
>> >
>> > The weird thing is my box was running fine for a few months prior to a
>> > power outage. After the outage I booted up the box and I started to
>> > notice IVTV buffer overflows happening during every recording causing
>> > the load to spike up to 10+ during each recording. The recording was
>> > useless of course too. This was with IVTV 0.4.1 on a PVR-500.
>> >
>> > So I decided to upgrade to IVTV 0.4.5 to see if that solved the
>> problem.
>> > Well, I no longer see IVTV buffer overflow messages in the log, but
>> now
>> > mythbackend uses 100% CPU. I upgraded to the latest SVN snapshot of
>> > 019-fixes branch to see if that helped at all, but it didn't.
>> >
>> > So now mythbackend uses 100% CPU, the recordings seem to be working
>> > fine, but I can't watch any recordings while this is happening.
>> >
>> > I'm running an Athlon 2100 with kernel 2.6.14.
>> >
>> > Just last week I could have two recordings going at once, mythcomm
>> flag
>> > running in real-time, and two frontends both watching recordings with
>> no
>> > issues at all. Now one recording at a time and NOTHING else is all
>> that
>> > can happen. :(
>> >
>> > Does anyone know what I can do to try and track this issue down?
>> >
>> > Thanks.
>> >
>> > On Fri, 2006-06-16 at 06:41 -0400, Jeff wrote:
>> >> On 6/15/06, Ryan Steffes <rbsteffes at gmail.com> wrote:
>> >>
>> >> > Do you, by any chance, have a slave to offload the transcode onto?
>> >> Try
>> >> > disabling transcode jobs on that backend, and see if it comes back.
>> >> Mine
>> >> > hasn't since then, even though it's a less than ideal fix.
>> >> >
>> >>
>> >> For the most part I don't do transcoding. I do have a 'transcode for
>> >> ipod'
>> >> job which seems to have gotten itself attached to every recording (it
>> >> was
>> >> only supposed to be one show) but I don't think its working at the
>> >> moment.
>> >>
>> >> I do commercial flagging though at the end of each show.
>> >>
>> >> I can try moving this to a slave backend.
>> >> _______________________________________________
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>> > --
>> > Mike Benoit <ipso at snappymail.ca>
>> > _______________________________________________
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>> >
>>
>>
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> --
> Mike Benoit <ipso at snappymail.ca>
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