[mythtv-users] SOLVED System Load/Performance Question

[Bob Cottingham]

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.

Bob