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-   -   No double buffering on second screen? (http://www.nvnews.net/vbulletin/showthread.php?t=24212)

squarooticus 01-29-04 12:00 PM

No double buffering on second screen?
 
What is the technical reason there is no double-buffering on the second screen on a single-card, dual-head setup? I run my X server with two separate screens (i.e., not twinview and not xinerama), and I get very noticeable tearing artifacts when watching DVD's on the second screen, which I assume is due to it not double-buffering.

Perhaps there's a way to fix this, especially since the nvidia proprietary driver keeps me from using a second (PCI) video card to do 2-D tasks at any reasonable speed. Any clues?

Andy Mecham 01-29-04 04:21 PM

From the README:

o Hardware that can only be used on one display at a time (eg:
video overlays, hardware accelerated RGB overlays), and which
consequently cannot be used at all when in TwinView, can be
exposed on the first X screen when each display is a separate
X screen.

Quote:

especially since the nvidia proprietary driver keeps me from using a second (PCI) video card to do 2-D tasks at any reasonable speed.
What do you mean? What pci video card?

--andy

squarooticus 01-29-04 04:33 PM

Quote:

Originally posted by Andy Mecham
From the README:

o Hardware that can only be used on one display at a time (eg:
video overlays, hardware accelerated RGB overlays), and which
consequently cannot be used at all when in TwinView, can be
exposed on the first X screen when each display is a separate
X screen.
I see: double buffering is one of those hardware features, I presume. That's too bad: do the Quadra cards support double buffering on multiple displays used as separate X screens?

Quote:

What do you mean? What pci video card?
So, on my old system (dual Athlon, AMD 76x) I used to use two entirely separate video cards for the dual heads: the AGP FX5600 I'm using now for screen 0, and a PCI GeForce2 MX 400 for secreen 1 on which I used to play DVD's while working. When I got my current machine (dual Opteron, AMD 81x1), this setup stopped working because the 2-D performance on the second display got *really* slow: I'm talking 2-3 frames/sec instead of 30.

I discovered this was a software problem (open source nv driver worked fine with that hardware configuration for 2-D, but has no 3-D acceleration) and emailed you and posted here about it, but got no useful response, so I switched to using two screens on the FX5600 card. Unfortunately, this setup has the lack-of-double buffering problem, so I'm not entirely satisfied with it, either.

Cheers,
Kyle

Andy Mecham 01-29-04 04:34 PM

Quote:

When I got my current machine (dual Opteron, AMD 81x1), this setup stopped working because the 2-D performance on the second display got *really* slow: I'm talking 2-3 frames/sec instead of 30.
What specific motherboard? I'll look into it.

--andy

squarooticus 01-29-04 04:37 PM

Quote:

Originally posted by Andy Mecham
What specific motherboard? I'll look into it.
Tyan Thunder K8W, which at the time had the 1.00 BIOS. (I have recently upgraded to the 1.01 beta BIOS, but have not tested this configuration since it's a PIA to keep switching in and out video cards. :) )

Thanks, Andy---I appreciate your looking into it.

Cheers,
Kyle

Andy Mecham 01-29-04 04:39 PM

Sure. The latest beta bios for the K8W is pretty much a necessity to work around mtrr problems (and to get any sort of AGP to work).

Final check - what distro?

thanks,

--andy

squarooticus 01-29-04 04:45 PM

Quote:

Originally posted by Andy Mecham
Sure. The latest beta bios for the K8W is pretty much a necessity to work around mtrr problems (and to get any sort of AGP to work).
Does this mean you want me to test my two-card setup under the new BIOS?

Quote:

Final check - what distro?
Debian unstable, pretty current (I do dist-upgrades every few days).

Cheers,
Kyle

Andy Mecham 01-29-04 04:46 PM

Quote:

Does this mean you want me to test my two-card setup under the new BIOS?
No, just wanted you to be aware. It wouldn't hurt to check, though.

--andy

squarooticus 01-29-04 04:50 PM

BTW, at the time I was using Linux 2.6.0-pre?? with the AMD-8151 agpgart module, since I don't believe the nvidia driver supported it natively (or does even now). Right now I have 2.6.1 with the same agpgart module, and am running the latest nvidia driver (5336).

Cheers,
Kyle

Andy Mecham 01-29-04 04:51 PM

Ah, you're running 32bit linux?

--andy

squarooticus 01-29-04 04:52 PM

Quote:

Originally posted by Andy Mecham
[b]Ah, you're running 32bit linux?
That's right. Do I need a 64 bit kernel for this mobo to be properly supported by the driver?

Cheers,
Kyle

Andy Mecham 01-29-04 04:53 PM

No, but it makes a difference in which distros I test with. :)

--andy


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