[mythtv-users] PIII 450-frontend: too slow?

Andrew Lynch lynchaj at yahoo.com
Sat Mar 11 00:13:27 UTC 2006



--- Al Bogner <mythtv-users at ml061.pinguin.uni.cc>
wrote:

> Am Freitag, 10. März 2006 19:52 schrieb Andrew
> Lynch:
> 
> Andrew,
> 
> > http://amicus.sourceforge.net
> 
> This is based on Debian. I have Debian-Sid _and_
> Suse 10 on this machine. With 
> Sid mythtv is unusable, it is a _lot_ slower. I have
> no idea why, it is the 
> same hardware. When I start KDE, the initial sound
> is interrupted with Sid, 
> but not with Suse.

True, AMICUS is based on Debian core but to be fair it
is very lightweight compared to the standard Debian
desktop install.  The default AMICUS install is very
lightweight using only X, fluxbox, and MythTV.  Only
the barest minimum features are installed.  Anything
more than that is installed by the user.

No Gnome or KDE or OO.o or anything like that to bog
down an older PC.  

You might want to give it a try and see for yourself.

> 
> > I recommend an NVidia card as it will give you
> good
> > performance on that hardware. I cannot say about
> the
> > ATI card.
> 
> Hmmh, maybe I exchange the card.
> 

I would.  NVidia makes great video chipsets and the
driver support is excellent in Linux.

> >
> > Also, I would recommend reducing screen resolution
> to
> > 640x480 and capture resolution to no greater than
> > 480x480. Make sure HD DMA is operating with
> hdparm.
> 
> I use PAL with DVB-S from Astra and Hotbird on the
> backend-machine. At the 
> moment there is no chance to scan Hotbird, while
> Hotbird (Diseqc) works with 
> scan and Kaffeine.
> 

> Why is the harddrive important, it is a frontend?
> 

The harddrive and the IDE chipset have to support DMA
transfers even on a frontend only machine because the
video is cached on the harddrive prior to display.  If
DMA is not working it will bog down the system
severely.

> Backend:
>  Timing cached reads:   1292 MB in  2.00 seconds =
> 644.67 MB/sec
>  Timing buffered disk reads:  102 MB in  3.03
> seconds =  33.64 MB/sec
> 
> Frontend
> Model=ST380021A
> Timing cached reads:   544 MB in  2.00 seconds =
> 271.98 MB/sec
>  Timing buffered disk reads:   36 MB in  3.01
> seconds =  11.95 MB/sec
> DMA: mdma0 mdma1 mdma2 udma0 udma1 *udma2 udma3
> udma4 udma5
> smbios.bios.version = 'ASUS P2B ACPI BIOS Revision
> 1014 Beta 003'
> 

That looks like the harddrive capabilities.  hdparm
sets the IDE controller to communicate with the
harddrive.  You need both the harddrive and IDE to
have the same capabilities to get maximum DMA
performance.

> I think this is too slow for this drive.
> WIth a fast machine and the same model I get with
> these values:
> Timing cached reads:   1360 MB in  2.00 seconds =
> 680.10 MB/sec
>  Timing buffered disk reads:  100 MB in  3.04
> seconds =  32.85 MB/sec
> 
> Maybe the hd is connected with an old IDE-cable or
> the ASUS P2B supports only 
> udma2.
> 

check with 

$apt-get install hdparm
$hdparm /dev/hda   <- your drive here.


> Al
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> 


Thanks!

Andrew Lynch


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