[mythtv-users] HD 1080i Jerky playback while recording
Steve Malenfant
smalenfant at gmail.com
Fri Jan 6 14:20:52 UTC 2006
The harddrive is a brand new samsung 200GB. Although, the HD Ring
Buffer might be set a bit high "14400" and maybe the jerkyness happens
when that buffer is written to disk.
I'll try to lower that quite a bit to see if it makes a difference...
Is there a way for mythfrontend to buffer more data so it doesn't
starve when mythbackend is busy doing something else?
Steve
On 1/5/06, Steve Adeff <adeffs at gmail.com> wrote:
> On Thursday 05 January 2006 23:02, Steve Malenfant wrote:
> > Scenario :
> > - Backend recording NBC in HD 1080i
> > - Frontend playing the NBC show in 1080i
> >
> > Result : Jerky playback
> >
> > As soon as the show finish recording, the playback is fine. If I do
> > the same on a recording in 720p, it doesn't happen.
> >
> > The only I could see is that the CPU is used at 45% and the "wa" state
> > uses the rest (0-1 % idle).
> >
> > Usage when recording on backend and watching on frontend :
> > top - 22:58:38 up 4:21, 4 users, load average: 1.90, 1.19, 1.13
> > Tasks: 117 total, 1 running, 115 sleeping, 0 stopped, 1 zombie
> > Cpu(s): 41.7% us, 3.3% sy, 0.0% ni, 0.3% id, 51.3% wa, 3.3% hi, 0.0%
> > si Mem: 1035872k total, 936812k used, 99060k free, 6528k buffers
> > Swap: 690752k total, 708k used, 690044k free, 579356k cached
> >
> > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> > 6293 root 15 0 379m 147m 19m S 42.3 14.6 1:19.09 mythfrontend
> > 3026 root 15 0 194m 60m 7720 S 1.7 6.0 3:09.03 X
> >
> > Usage when not recording and watching the same show :
> > top - 23:01:19 up 4:24, 4 users, load average: 2.40, 1.76, 1.35
> > Tasks: 117 total, 3 running, 113 sleeping, 0 stopped, 1 zombie
> > Cpu(s): 43.2% us, 0.7% sy, 0.0% ni, 55.1% id, 0.3% wa, 0.7% hi, 0.0%
> > si Mem: 1035872k total, 936116k used, 99756k free, 6788k buffers
> > Swap: 690752k total, 708k used, 690044k free, 576456k cached
> >
> > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> > 6293 root 15 0 382m 149m 19m S 42.0 14.8 2:59.47 mythfrontend
> > 3026 root 15 0 194m 60m 7720 S 0.7 6.0 3:19.36 X
> >
> >
> > Any ideas why the "wa" is using so much of the CPU time only when the
> > backend is recording?
> >
> > wa: Time spent waiting for IO. Prior to Linux 2.5.41, shown as zero.
> >
> > Steve M.
>
> sounds more like your harddrive is unable to keep up.
>
> --
> Steve
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