[mythtv-users] HD 1080i Jerky playback while recording

[Steve Malenfant]

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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