[mythtv-users] SOLVED System Load/Performance Question

Bob Cottingham bobnvic at gmail.com
Sat Feb 25 02:27:22 UTC 2006


On 2/24/06, Brian Wood <beww at beww.org> wrote:
> On Feb 24, 2006, at 5:20 PM, Bob Cottingham wrote:
> > On 2/24/06, Brian Wood <beww at beww.org> wrote:
> >> On Feb 24, 2006, at 3:00 PM, mrwester wrote:
> >>> This sounded like it could be related to problems I've been seeing
> >>> with ivtv corruption and prebuffering pauses, however with my
> >>> nforce2
> >>> chipset I can't adjust the pci latency for the IDE, audio or a few
> >>> other controllers, which are all set to 0.  I don't have a problem
> >>> changing the latency for the build-in video (which was set to
> >>> 248) and
> >>> the ivtv cards.  I found this to be the case for both nforce2 based
> >>> systems I tried.  I didn't find anything through google that really
> >>> addressed this issue.  Does anyone else see this?  Is this a
> >>> potential
> >>> issue?  Is there any reason to have the video card latency so
> >>> high?  I
> >>> lowered the video latency and I'm going to see what effect it has on
> >>> performance.
> >>>
> >>> Hi Bob-
> >>>
> >>> Did you come to any  resolution with this?  I've got an nforce2
> >>> system as well (chaintech) , and I cannot adjust pci latency for
> >>> IDE either...  I see a systematic stuttering (1 every 1.5 seconds
> >>> or so?) of CNN tickertape with my XP2900, FX5200 system, that I
> >>> can't help think it has something to do with PCI latency.  I get
> >>> occasional glitches in HDTV recordings as well, for example if
> >>> someone accesses mythweb while the recording is happening.  I think
> >>> this is all related, but like you, I'm not finding any answers by
> >>> google.  Thanks for any insight,
> >>>
> >>
> >> Every system I have checked (albeit only 4 of them) has had the
> >> graphics card set at 248. I've seen a couple of boxes (like my Dell
> >> P4) that had IDE set to 0, but I'm not running Myth on that one so I
> >> haven't played with it yet.
> >>
> >> The "0" value may be something special in the PCI/DMA setup, and may
> >> not mean what it seems to mean.I'm trying to learn more as well.
> >>
> >> You say you can't change the latency for the IDE system, what happens
> >> when you run setpci? Does it seem to work and just not set the value?
> >
> > I tried setpci -v -d "*:* latency_timer=b0 as discussed in
> > http://www-128.ibm.com/developerworks/library/l-hw2.html, and it
> > responded as though everything had been set to b0, however when I
> > reran lspci -v the only thing that had changed was the encoder cards
> > and the graphics card.  Everything else was still 0.  I think this may
> > mean that they aren't writeable and I don't know if the relatively
> > large values of 64 for each of my two encoder cards is significant or
> > if the 0 value simply means some special setting as you mentioned and
> > therefore isn't can't be directly compared.  I'm wonder because it
> > would apply to soundcard, LAN port and IDE channel.
>
>
> I'd be interested to know what host bridge chipset you have, I'm
> trying to accumulate data on as many as I can.
>
> My Dell with an Intel Tehama chipset (82850 850) behaves the same as
> yours, everything seems defaulted to 64 except for the graphics card
> (248) and the IDE interfaces and the bridges, which are zero. I think
> it has something to do with the way the bridges interact with the PCI
> system.
>
> Clearly we need more information on this. Like so many of the "fixes"
> we find, they work for some folks and not others. I think there are
> more variables than we are currently aware of that affect this matter.

It is an nForce2 IGP chipset.  Same response on two different nForce2
systems I have while a Via based system responded like you stated for
your Via system.


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