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Old 01-01-09, 12:26 AM   #13
schomin
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Default Re: problems with compiz and multiple cards

Quote:
Originally Posted by Dragoran View Post
simply connect the second monitor to the first card and use twinview?
Thats what i was doing. I bought the second card cause i thought i could use SLI with two monitors but apparently i can't. So instead i'm using them separately through xinerama. I did this to hopefuly see and increase in speed on each monitor (as they have dedicated video cards now). Now from what i've heard glx, xgl or AIGLX can be used along with xinerama to enable the composite extention but i could be wrong. I'm just looking for a way to get my desktop to behave the way it use to but with the two card two monitor setup.
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Old 01-01-09, 05:43 AM   #14
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Default Re: problems with compiz and multiple cards

Even if it were somehow possible (perhaps using XGL but I have my doubts about it) to use a 'xinerama'-like setup using two cards the performance would suck especially in cases where you have to move windows between the two displays. The main performance issues of compiz/kwin are related to copying pixmaps (windows, bitmaps) from system memory to video memory 'when needed'. This is quite complicated as you don't want to move pixmaps around all the time as it is slow, when it is in video memory you want to keep it there. When you move windows or so between two displays in a setup with two cards you have to a lot of moving from card 1 to card 2 which is very inefficient and this kills performance.

I believe on Windows Nvidia offers these days twinview in sli mode. If that's correct they likely didn't take the time to port it to Linux yet (read no big customers asked for it).
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Old 01-01-09, 12:04 PM   #15
schomin
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Default Re: problems with compiz and multiple cards

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Originally Posted by Thunderbird View Post
Even if it were somehow possible (perhaps using XGL but I have my doubts about it) to use a 'xinerama'-like setup using two cards the performance would suck especially in cases where you have to move windows between the two displays. The main performance issues of compiz/kwin are related to copying pixmaps (windows, bitmaps) from system memory to video memory 'when needed'. This is quite complicated as you don't want to move pixmaps around all the time as it is slow, when it is in video memory you want to keep it there. When you move windows or so between two displays in a setup with two cards you have to a lot of moving from card 1 to card 2 which is very inefficient and this kills performance.

I believe on Windows Nvidia offers these days twinview in sli mode. If that's correct they likely didn't take the time to port it to Linux yet (read no big customers asked for it).
Just for the record I do have the two cards and monitors setup in xinerama. As you said dragging between screens does cause smearing and is probably not the greatest. What i am mainly worried about though is performance once the application is on one screen or another. I'm planning to overclock the pcix to maybe get a little bit better performance between monitors. I'm hoping to see twinview in SLI soon as this is what i wanted to originally do. Eventially though i want to get a quadro because it has better linux support from what I've seen and will give me better performance for my work. Also does anyone know if twinview will be in Linux on SLI ever?
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Old 01-01-09, 06:59 PM   #16
JaXXoN
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Default Re: problems with compiz and multiple cards

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Originally Posted by Thunderbird View Post
Even if it were somehow possible (perhaps using XGL but I have my doubts about it)
Look at this and be amazed :-)

http://www.youtube.com/watch?v=1DWzuIreDGA

Here are the instructions:

http://meandubuntu.wordpress.com/200...ama-on-nvidia/
http://ubuntuforums.org/showthread.php?t=884161

However, since XGL has been abandoned, i fear this is nothing you would
like to use in a production system - what a pity.

Bernhard
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Old 01-02-09, 12:01 AM   #17
schomin
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Default Re: problems with compiz and multiple cards

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Originally Posted by JaXXoN View Post
Look at this and be amazed :-)

http://www.youtube.com/watch?v=1DWzuIreDGA

Here are the instructions:

http://meandubuntu.wordpress.com/200...ama-on-nvidia/
http://ubuntuforums.org/showthread.php?t=884161

However, since XGL has been abandoned, i fear this is nothing you would
like to use in a production system - what a pity.

Bernhard

Thanks that'll do until i get my quadro and from what i've seen the quadro does have support for what i want.
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Old 01-02-09, 12:07 AM   #18
schomin
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Default Re: problems with compiz and multiple cards

Also is AIGLX included with the default xserver setup?
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Old 01-02-09, 05:15 AM   #19
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Default Re: problems with compiz and multiple cards

What makes you believe a Quadro does what you want? There is a quadro with four outputs but it are just two GPUs on a single board. Further functionality wise for twinview/xinerama there isn't a real difference between a Geforce and a Quadro. Only QuadroPLEX is really different but that's bloody expensive.
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Old 01-02-09, 07:56 AM   #20
schomin
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Default Re: problems with compiz and multiple cards

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Originally Posted by Thunderbird View Post
What makes you believe a Quadro does what you want? There is a quadro with four outputs but it are just two GPUs on a single board. Further functionality wise for twinview/xinerama there isn't a real difference between a Geforce and a Quadro. Only QuadroPLEX is really different but that's bloody expensive.
On the nvidia website it specifies under quadro and SLI frame rendering exactly what i want:

SLI Multi View: Combines the power of two identical NVIDIA Quadro PCI Express graphics cards to drive multiple displays, with each GPU dedicated to a single display or to a pair of displays.
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Old 01-02-09, 08:25 AM   #21
JaXXoN
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Default Re: problems with compiz and multiple cards

Quote:
Originally Posted by schomin View Post
SLI Multi View: Combines the power of two identical NVIDIA Quadro PCI Express graphics cards to drive multiple displays, with each GPU dedicated to a single display or to a pair of displays.
"MultiView" = "Xinerama":

http://www.nvnews.net/vbulletin/show...17&postcount=4
http://www.nvnews.net/vbulletin/show...26&postcount=8

regards

Bernhard
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Old 01-02-09, 09:55 AM   #22
schomin
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Default Re: problems with compiz and multiple cards

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Originally Posted by JaXXoN View Post
Thanks for the clarification. So this is exactly what I'm doing now. I just wanna see a performance increase on each screen. If this isn't possible Ill get a 280 I guess.

Will I see a performance increase running a program on eachscreen?
and would PCIe slot overclocking increase performance between screens?
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Old 01-03-09, 11:25 AM   #23
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Default Re: problems with compiz and multiple cards

bump.......
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Old 01-03-09, 01:14 PM   #24
JaXXoN
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Default Re: problems with compiz and multiple cards

BTW.: there do exist "compiz DMX plugins", i.e.
http://rpm.pbone.net/index.php3/stat....i586.rpm.html

However, i have no idea what these plugins are doing and it's not easy to find
out trough google :-)

From what i understand, DMX basically also requires xinerama for a full desktop,
but maybe it is possible to get around this on window manager level using these
compiz DMX plugins?

I guess it would be possible to use DMX locally on a single machine.

Would be interesting if such a solution would be performant enough.

regards

Bernhard
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