On Sun, 2008-05-04 at 09:32 -0400, JP Fournier wrote:
> Andy Walls wrote:
>
> >>
> >
> > I also notice that your HD-5500 card and PVR-250 card are on the main
> > PCI bus Segment 0, but that the PVR-500 is on bus segment 2 behind the
> > Hint Corp bridge. You could try moving the PVR-250 over to bus segment
> > 2 or the PVR-500 over to bus segment 0, to see if things are better when
> > they're on the same bus segment.
> >
>
> Hmnn. How do I go about doing this? I thought that physically moving
> the card would accomplish this, but no matter what slot I put it in,
> lspci reports the same. Right now it is sitting in the slot that
> previously contained the 5500:
Hmmm. The most logical explanation is that the Hint Corp bridge is on
the PVR-500 card and the CX23416's sit behind it. If that's the case,
you can't do what I suggested.
I still am inclined to believe some sort of VIA chipset errata is to
blame, but since VIA Tech doesn't appear to make their datasheets and
errata sheets readily available, I'm not hopeful that you'll ever find
the root cause or a solution.
But if you're interested in looking around for problem indicators,
there's still a chance to observe things:
1. Before running any captures, does the "Status:" line for any device
in the output of "lspci -vv" have a "+" next to SERR, PERR, ParErr, or
any of the Aborts?
2. What about with one capture ongoing?
3. Can you write a script/program to capture the output "lspci -x"
periodically, and then start a second capture? ("lspci -F foo -vv" can
then be used to parse the saved output later.)
I'm really expecting SERR+ to happen somewhere.
And some more questions (not that they'll lead to any solutions):
A. Do you have the symptoms with just the PVR-500 in the machine without
the PVR-250?
B. Do two captures simultaneously from the PVR-500 go OK?
C. Do you have the symptoms when you perform two captures, not using
MythTV, but just using
$ cat /dev/video0 > foo0.mpg &
$ cat /dev/video1 > foo1.mpg
?
D. Could you provide the full output of "lspci -vvx" so I can look at
the latency timer settings and MIN_GNT and MAX_LAT, in the context of
your total system? The ratio of MIN_GNT/MAX_LAT, or MIN_GNT/(MAX_LAT +
MIN_GNT) depending on the vendor, can tell you what fraction of the PCI
bus bandwidth a manufacturer says it's device needs at a minimum in a
worst case situation. If a device has no value for MAX_LAT, any
fraction of the PCI bus bandwidth greater than 0 is acceptable for that
device. If the ratios of all these fractional of bus bandwidths add up
to greater than 1.0, you're bound to have some occasional performance
problems, but mystery reboots would still be unexpected.
-Andy
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