[mythtv-users] Fast CPU, DMA enabled on HD, Xv enabled, still getting pauses in Live TV

Tue Aug 19 01:44:29 EDT 2003

Okay, now I'm starting to go nuts.  I've gone through
the mailing-list archive, and have tried all sorts of
things.  Changing DMA parameters, recompiling MythTV
with -march=xthlon-xp, trying "nice" on mythbackend,
and several other things.  And I'm still getting
skips, and with this hardware, I don't see how I could
be having problems.  All I want to do is run
mythbackend and mythfrontend on the same PC without
stuttering in the video/audio.

Perhaps based on my hardware/software setup, somebody
can make some additional recommendations.

Hardware:
- Albatron KX400-8X motherboard (brought the ECS board
back to Fry's, too many problems) - VIA KT400 chipset
- Athlon XP 2400+ CPU (2GHz real speed, 266MHz FSB)
- 512MB RAM (DDR333) - the BIOS indicates that the RAM
is running at 133MHz * 2.5 (333MHz)
- Matrox G400 Dual-Head (hooked up to a monitor, so
using Xv)
- Western Digital Hard Drive UDMA 100
- Soundblaster Live! 5.1 (using in full-duplex mode
with kernel drivers)
- Leadtek Winfast TV 2000 XP (I put in gbuffers=8)
- Tulip clone Ethernet card (no onboard NIC)

Software:
- Red Hat Linux 9
- Recompiled the kernel, Linux-2.4.21, included the
low-latency and preempt patch
(/proc/sys/kernel/lowlatency shows 1)
- Before compiling any software, I set CFLAGS and
CPPFLAGS to -march=athlon-xp
- MythTV 0.11
- Killed off as many of Red Hat's services as possible
- Using twm as the window manager.

hdparm -Tt shows:
/dev/hda:
 Timing buffer-cache reads:   128 MB in  0.41 seconds
=312.20 MB/sec
 Timing buffered disk reads:  64 MB in  1.42 seconds =
45.07 MB/sec

I'm using ext3 filesystems for everything, two
partitions, one for root, one for /home. which is
where MythTV files are stores (using symlinks from
/mnt/store).  The ext3 filesystem is mounted with
noatime, and in grub.conf, I put in
rootflags=data=writeback.

I'm not really stressing things out, I'm recording
RTJPEG at 480x480, MP3 quality 7.  Switching to MPEG4
(as suggested in a post in the mailing-list) didn't
help any.  I have plenty of CPU time (it never goes
higher than 50% user, never less than 30% idle.  Not
using jitter control, not using experimental A/V sync,
just using the default options.

The only thing that I can think might possibly causing
some problems is that I have only one hard drive for
everything.  Either that, or I do I need a real 2.4GHz
machine (i.e. Intel?)

Please folks, any suggestions?  Any at all?

-- Joe

--- Joe V <joevph at yahoo.com> wrote:
> Brian,
> 
> Well, it helps a bit...  I upgraded to bttv 0.7.107
> (and specigied gbuffers=10), put my hard drive and
> DVD-ROM on seperate cables (don't know if that will
> help much), as well as forcing 32-bit operations,
> and
> the stutters, when they happen don't cause such as
> big
> of a delay.
> 
> I don't recall any stutters last night when I put my
> DDR400 module (running at DDR266) from my desktop in
> the machine with those changes (watching for a good
> 30
> minutes), so it could be a memory bandwidth issue as
> well as a bttv driver issue (and maybe the HD).
> 
> I'll keep experimenting and see what works.
> 
> Are you using your machine as just a frontend, or as
> both frontend and backend (as I'm doing)?
> 
> -- Joe
> 
> --- Brian <brian at boid.isa-geek.com> wrote:
> > 
> > I'm having no issues running .11 with a k7s5a,
> duron
> > 1.1, 512mb of pc133, ata100 drives, TV Wonder VE,
> > generic 2.4.21, bttv 0.7.107 (Could not get 0.9.x
> to
> > run properly)
> > 
> > Hope this can help point you in the right
> direction
> > :/
> > 
> > Cheerios
> > 
> > :)
> > 
> > On Sat, 16 Aug 2003 23:37:16 -0700 (PDT)
> > Joe V <joevph at yahoo.com> wrote:
> > 
> > > This is completely strange, I don't understand
> it.
> > > 
> > > I upgraded to an AMD Athlon XP 2400+ (real
> speed,
> > > 2GHz), with an ECS KS57A Pro motherboard today. 
> > The
> > > motherboard isn't the greatest, but for $89.99
> for
> > the
> > > combo, you can't really beat that.
> > > 
> > > Anyway, I have my profile for Live TV setup for
> > > 480x480, RTJPEG, MP3 Audio compression, level 4
> > > (middle of the pack or so).  When I run "top", I
> > see
> > > that mythbackend ranges from 20-43% (CPU), and
> > that
> > > mythfrontend ranges from 3-15%.  I have DMA
> > enabled on
> > > my hard drive (hdparm shows this), XVideo is
> > enabled
> > > on the second head of the Matrox G400 I'm using.
> 
> > The
> > > card being used is a Leadtek Winfast TV XP 2000
> > Deluxe
> > > (bttv), and I'm using the 2.4.21 kernel,
> unpatched
> > > from kernel.org.
> > > 
> > > Despite this, I still get a stutter in the
> > video/audio
> > > every now and then (if you average it out,
> > probably
> > > once every ten minutes).  The output of "top"
> > doesn't
> > > seem to spike any, so I don't think that it's
> the
> > CPU
> > > not being powerful enough (it should be).
> > > 
> > > I've tried a bunch of things...  Swapping RAM
> > > (currently I'm using PC133, but I took the
> DDR400
> > from
> > > my desktop out and tried it), I've tried not
> > enabling
> > > the second head on the Matrox (using a monitor),
> > using
> > > ALSA and OSS, using KDE and Blackbox, heck,
> almost
> > > everything I could think of except changing the
> > video
> > > card (maybe that's it?).  I've also turned off
> > > unnecessary services in Red Hat 9 (turned off
> > > sendmail, cups, etc.).
> > > 
> > > Does anybody have any further suggestions?  At
> > this
> > > point, I'm almost suspecting a hardware problem
> of
> > > some sort.
> > > 
> > > -- Joe
> > > 
> > > __________________________________
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> 
> 
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