[mythtv-users] stutter while recording two programs at once

Brad DerManouelian myth at dermanouelian.com
Sun Sep 10 23:19:03 UTC 2006

On Aug 29, 2006, at 6:43 PM, Judd Tracy wrote:

> On 8/29/06, Brad DerManouelian <myth at dermanouelian.com> wrote:
>> On Aug 29, 2006, at 10:15 AM, Steven Adeff wrote:
>>> On 8/29/06, Tony Lill <ajlill at ajlc.waterloo.on.ca> wrote:
>>>> Brad DerManouelian <myth at dermanouelian.com> writes:
>>>>> I've got an AMD64 box with a SATA II drive formatted as JFS
>>>>> dedicated
>>>>> to recorded programs. music, photo, videos are on a separate SATA
>>>>> drive and the system runs from a PATA drive - all are 7200 RPM  
>>>>> with
>>>>> 8MB buffers.
>>>>> I've got a PVR-350 and an HD-5500 card in the box which is also my
>>>>> frontend. I'm getting weird stuttering when recording on both  
>>>>> tuners
>>>>> at the same time. The HD stream looks perfect but the stream from
>>>>> the
>>>>> PVR-350 will show a single frame from about a second before the
>>>>> current position. It happens intermittently but often enough to be
>>>>> REALLY annoying. I've found that it's in the recording this way
>>>>> since
>>>>> the rogue frames happen at the same place when I play back every
>>>>> time. I have a feeling it MIGHT only be happening when watching a
>>>>> program and recording two others at the same time. I had  
>>>>> anticipated
>>>>> 3GB/sec on the SATAII drive would be enough bandwidth to watch 1,
>>>>> record 2. Is this not the case? Is there a good way to test? Do I
>>>>> finally need to submit and start transcoding every program I watch
>>>>> and deal with sub-par quality?
>>>> Are you getting any messages from the ivtv driver about your
>>>> application not reading fast enough? Look in
>>>> /var/log/messages.
>>>> There's a known problem where database access slows
>>>> things down enough to cause dropped frames. It's more likely to
>>>> happen
>>>> in the first minute of the recording, 'cause it hits the database
>>>> more
>>>> often then.
>>> it may also be a pci latency issue, I had similar occur with a  
>>> card I'm using for part of my RAID array once I changed the latency
>>> this went away.
>> The only thing that looks like an error or warning in my /var/log/
>> messages is:
>> Aug 27 16:11:13 mythtv kernel: ivtv0: Unreasonably low latency timer,
>> setting to 64 (was 32)
>> Oh.. and ssh attacks attempted and failed on my system. :)
> Try taking a look at this:
> http://www.mythtv.org/wiki/index.php/PCI_Latency
> Judd

/sbin/lspci -v
tells me:
00:07.0 IDE interface: nVidia Corporation CK804 Serial ATA Controller  
(rev f3) (prog-if 85 [Master SecO
         Subsystem: ASUSTeK Computer Inc.: Unknown device 815a
         Flags: bus master, 66Mhz, fast devsel, latency 0, IRQ 225
         I/O ports at 09f0 [size=8]
         I/O ports at 0bf0 [size=4]
         I/O ports at 0970 [size=8]
         I/O ports at 0b70 [size=4]
         I/O ports at d800 [size=16]
         Memory at ad002000 (32-bit, non-prefetchable) [size=4K]
         Capabilities: <available only to root>

00:08.0 IDE interface: nVidia Corporation CK804 Serial ATA Controller  
(rev f3) (prog-if 85 [Master SecO
         Subsystem: ASUSTeK Computer Inc. K8N4-E Mainboard
         Flags: bus master, 66Mhz, fast devsel, latency 0, IRQ 233
         I/O ports at 09e0 [size=8]
         I/O ports at 0be0 [size=4]
         I/O ports at 0960 [size=8]
         I/O ports at 0b60 [size=4]
         I/O ports at c400 [size=16]
         Memory at ad001000 (32-bit, non-prefetchable) [size=4K]
         Capabilities: <available only to root>

So I did this:
[mythtv at mythtv ~]$ sudo /sbin/setpci -v -s 00:07.0 latency_timer=b0
00:07.0:0d b0
[mythtv at mythtv ~]$ sudo /sbin/setpci -v -s 00:08.0 latency_timer=b0
00:08.0:0d b0

But /sbin/lspci -v still tells me latency 0 for both devices.

I feel dumb that I can't read directions and get this to work how I  
think it will work.

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