Multi-screen issues

[koffiejunkie]

Hi guys,

So I have three screens at work, with two identical nVidia cards (8200 I think) - one PCIe, one PCI. So far I've only been using two screens, but I would really like to have all three working. The requirement is:

* One large desktop
* Full 2D acceleration on all screens. 3d Would be nice but not necessary.
* When I maximise an app, I expect it to maximise to one screen, not across all three.

This works just fine with two screens connected to one card, with the nVidia driver, using TwinView. But when I add a third screen to the mix one of the following happens:

1. Two screens are configured on one X instance with TwinView, the third on a separate instance. This causes apps on the TwinView screens to maximise across all screens.

2. Three instances of X, no TwinView. This works but I can move an app from one screen to another. That's a problem for me.

3. Xinerama. This gives me the expected maximise behaviour, I can move things across screens, but there's no (or reduced) 2D acceleration. Something simple like page-up/page-down in less causes the CPU to spike.

From what I've heard, what I'm looking for might be possible with two Radeon cards with the ATI driver. Can anyone confirm?

 

[MyWorld]

Something like this?

[video=youtube;UhMErNsEoZw]http://www.youtube.com/watch?v=UhMErNsEoZw[/video]

http://ubuntuforums.org/showthread.php?t=884161

 

[koffiejunkie]

Something like this?

http://ubuntuforums.org/showthread.php?t=884161

Seems like it, thanks. I'll dig into this thread.

 

[fskmh]

IMO the twinview option is the easiest. Here is what I normally do with a dual-screen setup, (usually with one DVI output and one analogue VGA output on the same nvidia card):

• Install proprietary nVidia or cuda driver.
• Set up the screens in X with the nvidia-settings tool.
• Save the current config and then add/move it to /etc/X11/xorg.conf

If I was going to add a third screen connected to a second discrete card, I would manually add another "Device" section to xorg.conf and check that it's working before doing the configuration with nvidia-settings.

I know it's no longer necessary to have an xorg.conf file, but my experience has been that leaving everything to autoconfig is not always desirable, especially when you're trying to tweak things needed for desktop effects.

 

[koffiejunkie]

IMO the twinview option is the easiest. Here is what I normally do with a dual-screen setup

That's what I have already.

If I was going to add a third screen connected to a second discrete card, I would manually add another "Device" section to xorg.conf and check that it's working before doing the configuration with nvidia-settings.

Are you suggesting TwinView can work properly with three screens? That has not been my experience so far?

 

[fskmh]

Are you suggesting TwinView can work properly with three screens? That has not been my experience so far?

I've only had experience with two screens, so I have no idea. Just saying what I would try.

 

[koffiejunkie]

I've only had experience with two screens, so I have no idea. Just saying what I would try.

Right. So I can tell you with confidence that it doesn't work. I suppose that's why they went with TwinView rather than something like MultiView. I hope the upgrade it at some point

 

[fskmh]

Looks like you're stuck with nouveau and Xinerama then:

http://nouveau.freedesktop.org/wiki/MultiMonitorDesktop

 

[ponder]

From what I've heard, what I'm looking for might be possible with two Radeon cards with the ATI driver. Can anyone confirm?

No idea but I know Eyefinity supports 3 monitors off the bat. Dunno how well it works in linux though. If you can borrow a card from someone play around with it and see if it works is all I can suggest.

Wonder how far Wayland has come along, maybe it can do it with nvidia using the nouveau drivers. Maybe do a bit of googling as I recall reading something about wayland doing multimonitor support 'correctly'.

Future versions of RandR is suppose to support multi GPU setups.

 

[MyWorld]

Have you sorted this yet?

[video=youtube;O8747PFUDhY]http://www.youtube.com/watch?v=O8747PFUDhY&feature=g-u-u&context=G29c313aFUAAAAAAAAAA[/video]

If you have money to spare.

 

[koffiejunkie]

No idea but I know Eyefinity supports 3 monitors off the bat. Dunno how well it works in linux though.

He he! That's always the question, isn't it?

Wonder how far Wayland has come along, maybe it can do it with nvidia using the nouveau drivers. Maybe do a bit of googling as I recall reading something about wayland doing multimonitor support 'correctly'.

Yeah, I'm hoping Wayland breaks away from the X11 compatible brain damage.

Have you sorted this yet?

Unfortunately I haven't had time. And I'm a bit put off by how monkeying about with xinerama broke my KDE taskbar (or whatever they call it these days). It somehow remembered the wider screen, so the right side ran off screen but not onto the second display. I had to nuke quite a bit of .kde/ content before it went back to being normal.

Maybe I'll get to it this week.

http://www.youtube.com/watch?v=O8747PFUDhY&feature=g-u-u&context=G29c313aFUAAAAAAAAAA

If you have money to spare.

Interesting. But will that work in Linux? Windows already does what I want (has for more than a decade) so I know I'm not dealing with a hardware limitation.

 

[koffiejunkie]

So just an update, I finally got time to look at this (came to the office on a sunday evening). I have three instances of X, nVidia driver, xinerama. KDE then allows me to tweak the details for multiple monitors.

But it's extremely sluggish. And while glxgears works fine, I can't playback video at all - it's far too slow. This is a Core 2 Quad with 8GB RAM and two nVidia cards

I'll find some time to try things discussed in the link, but I'm seriously starting to think just switching back to Windows will be the most productive move

 

[ponder]

xinerama is a POS. You won't get any decent performance with it as I don't think it allows any direct rendering and it has to start an instance of everything on both cards.

KDE 4.9 is 'suppose' to have wayland support in 4.9. You can however compile kwin with wayland support from what I have read if you want to play around with it.

 

[koffiejunkie]

xinerama is a POS

Correction: X, and anything to do with it, is a POS. Xinerama is a POS but it only exists because X is such a POS.

I really really really hope Wayland isn't going to be another X with all the same problems and limitations.

KDE 4.9 is 'suppose' to have wayland support in 4.9. You can however compile kwin with wayland support from what I have read if you want to play around with it.

Thanks for that. I might invest some time checking that out - see if it's worth waiting.

 

[koffiejunkie]

So I thought it would only be polite to update you on how this turned out. I tried everything described in the links provided. The ubuntoforums link seems to be slightly dishonest about which features work and which don't when the six screen setup is going. Either that, or some serious magic happens when you add a 3rd card. Or maybe that was so long ago that the version of X he was using was from before the X.org developers broke all the useful things in favour of the eyecandy. Who knows.

Either ways, out of all the configurations I tried, I always got at most two of the three things I wanted going:

[1] hardware 2D acceleration (3D would be nice but not necessary)
[2] one big desktop
[3] physical screen boundaries (i.e. maximise and app and it goes over one screen).

For a while, I used three individual instances of X. This at least gave me a half usable desktop in terms of speed, but it was far too restrictive - can't move applications from one screen to the next, for example. Can't open multiple instances of some applications. Can't click on a link in Thunderbird on one screen and have it open in FireFox on another.

The last configuration I tried was two instances, two screens in one instance (with broken twinview) and the third screen on its own. This wasn't too slow, but X copy/paste behaviour was seriously messed up. Some copy operations wouldn't "take" causing me to paste the wrong thing into a terminal. You can imagine how disasterous this can be.

Anyway, ended up having our IT people load Windows 7 on my box. Makes life easier for them, my three screens work as expected. Firefox doesn't seem to leak memory as badly, flash plugin doesn't make my box crawl There was more than the screens that lead to this decision. I'm using MS Office much more heavily in my current position, Outlook in particular, and there really isn't a good alternative way to work seamlessly with colleagues.

Not to say there aren't things I'm missing and find frustrating. Highlight/paste style copy/paste is the most obvious. But hey, I'm getting more done now, so I won't complain too much.

Thanks for all the suggestions either ways!