[mythtv-users] Re: Shuttering video in myth
fpikus at gmail.com
Sun May 29 17:07:17 UTC 2005
On 5/29/05, Axel Thimm <Axel.Thimm at atrpms.net> wrote:
> On Sat, May 28, 2005 at 11:06:24PM -0700, Fedor Pikus wrote:
> > I'm mostly done putting together the myth box, but I ran into a
> > problem I did not expect, not with the hardware I put together: video
> > playback is stuttering quite badly. It does not happen all the time,
> > but mostly in these two cases:
> > 1) After I switch channels in live tv, there is a pause (expected),
> > then it starts playing, pauses, resumes, does it several times, this
> > lasts for 10-20 seconds, then it starts playing ok.
> > 2) If I pause live tv and then play it after a while, video stutters
> > and pauses, and it gets worse the longer I wait. If I paused for an
> > hour, it'll be impossible to watch, it'll halt every few seconds for
> > half a second, and unlike the case above, there is no end to this.
> > I'm running FC3, 2.6.11 kernel, latest myth and ivtv from atrpms (myth
> > 0.18.1-111, ivtv-0.3.5l-92).
> > The box is built around Soyo Dragon2 motherboard, Athlon 3200+ CPU,
> > 2GB of dual-channel RAM.
> > When video stutters, I often see disk light come on, especially in the
> > second case, so here is more about disks. There are 4 Seagate 300GB
> > ATA disks in the box, with two software RAIDs:
> > /dev/md0 mounted as /, raid1 built from hdb1, hdc1, 20GB, ext3
> > /dev/md1 mounted as /raid and used for all mythtv files, raid5 built
> > from hdb3, hdc3, hde3, hdf3 (currently runs in degraded mode until I
> > add 5th disk), about 1TB, JFS.
> > hdX2 are swap partitions, 1G on each disk, striped.
> > Seems like I need to tune the system for beter I/O performance. Any tips?
> Could you check the relevant folders (/raid) with bonnie++?
This is what bonnie reports:
Version 1.03 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
myth 4G 34966 82 66383 18 25916 7 33696 76 97975 22 200.6 0
------Sequential Create------ --------Random Create--------
-Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 2651 4 +++++ +++ 1350 1 1214 4 +++++ +++ 1102 3
> Is the live buffer also under /raid?
Fedor G Pikus (fpikus at gmail.com)
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