[mythtv-users] New installation, choppy video (not DMA) help request

[Raphael Pooser]

Dan wrote:
> This message is in reply to "Marcone at xs4all" via gossamer-threads.com.
> I initially subscribed to digests and switched this AM since people were
> responding pretty quickly.  I didn't get the message but saw it on the
> archive.  Apologies for thread-busting....
>
>   
>> Have you actually measured the throughput of your disk? I set up a new 
>> machine recently and at first it was using the "generic IDE" driver, 
>> which caused extremely poor disk performance and high CPU usage while 
>> accessing the disk, even though hdparm showed DMA being used. After 
>>     
>
> I ran hdparm -t but am unsure if this is a sufficient test or
> how to interpret the numbers.  They are below:
>
> [root at localhost log]# hdparm -tT -i /dev/hdd
>
> /dev/hdd:
>
>  Model=WDC WD400BB-75CAA0, FwRev=16.06V16, SerialNo=WD-XXXXXXXXXXXX
>  Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
>  RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=40
>  BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=16
>  CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=78125000
>  IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
>  PIO modes:  pio0 pio1 pio2 pio3 pio4 
>  DMA modes:  mdma0 mdma1 mdma2 
>  UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5 
>  AdvancedPM=no WriteCache=enabled
>  Drive conforms to: device does not report version: 
>
>  * signifies the current active mode
>
>  Timing cached reads:   4356 MB in  2.00 seconds = 2177.86 MB/sec
>  Timing buffered disk reads:  142 MB in  3.03 seconds =  46.83 MB/sec
>
> I don't know if cached/buffered covers the full range of relevant
> drive performance metrics for MythTV.
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>   
Actually those speed tests are on par with what you should be getting 
for a typical IDE drive and should be fine in mythtv.
To answer a previous post, fglrx supports TV out on most cards that the 
driver itself supports (not all, just check the readme on ati's site).  
TV out will most of the time work just by plugging in the TV-out and 
leaving the monitor disconnected, and restarting your computer after 
installing fglrx.  If fglrx is working properly then xv should work 
properly too; make sure to add the option to xorg.conf using ati-config 
if the option isn't already there in the device section.
However, based on the output of xvinfo you provided a link to, it looked 
to me like you had xv working with "radeon"... so maybe the problem is 
elsewhere?  Or perhaps xv just works better with fglrx, not sure on that 
one.  I know I never got any kind of good video playback without fglrx, 
then again I had to use fglrx to get tv out.
Raphael