Re: [vizstack-users] viz-desktop should now work with bezels

[Kumar, S. <shr...@hp...>]

> You're arranging the blocks in rows and disabling the right-most output 
>of each row -  explaining it like that should help . . . but I've spent 
> the whole evening trying to think of a good concise way to explain it, 
> and so far nothing. I'll think about it some more and see if I can suggest 
> anything, but it really is quite hard to explain clearly. 

I'm hoping to add some images. Can't think of anything better for now.

> One question: is it possible (or meaningful) to use a value of [None,1] 
> or similar? It seems like it would disable the first output on the GPU 
> rather than the second, which might be useful in some cases . . .

The first element corresponds to the clipping applied to the last column.
The second element corresponds to the clipping applied to the last row.

Using [None,1] would clip all displays that form the last row. E.g. if you were
driving [1,2] from every GPU, this would be useful. If you were using a 
QuadroPlex, both would elements could be used together, since it can drive upto 
4 displays as one unit.

> Also, does it /have/ to be the last GPU in the row? It might be nice to be 
> able to set up, say, a 5x5 display with the odd monitor in each row being in 
> the middle. Obviously very low priority, but still possibly useful. Also, how 
> hard would it be to support arbitrary mixing of different types of blocks? We 
> have a 5x5 system (completely unrelated to the stuff I'm working on right now 
> - it uses CGLX as the display system) which has the fifth column made up of two 
> vertical pairs and a singleton, with the rest of the display made up of horizontal 
> pairs - as it stands I think Vizstack would have to have the whole fifth column 
> made up of singleton monitors. In practice it's probably not an issue, but if 
> supporting arbitrary mixes of blocks is easy it might be something to consider 
> for a future version.

Good points. To me, arbitrary mixing of different types of blocks is the way to go.
The current mechanism is a quick plug; it is something easier to understand and
configure, but with the drawback of not handling all cases.

Setting up arbitrary mixing of blocks is not difficult. However, preventing 
users from making mistakes, and describing arbitrary layouts is where the work is.
Visualizing mix of blocks poses a problem too, perhaps a GUI is the best way to 
create them (and not command line tools OR handwritten config files.)

Also, with arbitrary blocks, we need some more "intelligence" in scripts for
applications that can't handle all types of Tiled Displays.

I've never used CGLX before. However, I have asked them for a password to download. 
Could you describe how you've configured your CGLX tiled display ?

Quite by coincidence, I did some reading about CGLX yesterday (A paper on
CGLX is getting published in TCVG). Do you think it makes sense to use
CGLX inside VizStack ? That way, GPUs could be used for CGLX or other
purposes on demand.

> And one final question: if you have a single GPU with four outputs, would 
> you have to make each block 4x1, or could you make them 2x2? i.e. to get 
> a 3x2 display would you need to have two rows of 4x1 blocks, or could you 
> use one row of 2x2 blocks? I doubt there's any hardware out there where 
> this would be an issue, but I imagine there's stuff on the horizon . . .

You would be able to make each block 4x1 or 2x2, or anything in between
(that's what we support for the QuadroPlex block).

Do you have any GPU that supports 4 displays ? Your QuadroNVS is actually 
two GPUs in one, with each capable of driving 2 displays at once. 

Current nVidia cards support 2 displays in one, and they call that support 
"TwinView". They will come out with more, and configuring them will need 
additional options in the config file I guess. When such GPUs are available, 
we will handle them. 

Regards
-- Shree

-----Original Message-----
From: Sim...@cs... [mailto:Sim...@cs...] 
Sent: Thursday, May 27, 2010 7:47 PM
To: viz...@li...
Subject: Re: [vizstack-users] viz-desktop should now work with bezels

> -----Original Message-----
> From: Kumar, Shree [mailto:shr...@hp...] 
> Sent: Thursday, 27 May 2010 3:57 PM
> To: viz...@li...
> Subject: Re: [vizstack-users] viz-desktop should now work with bezels
> 
>  
> I'm an atheist, but will take the compliments :-)
> 
> > Aside from being caught out at first by using 'none' instead of 
> > 'None', and having to rearrange the cabling (thankfully 
> displayport is 
> > much nicer than DVI in that regard), it was as simple as 
> creating the 
> > tiled display and adding the clip_last_block line. Running 
> from the console works perfectly.
> 
> Yeah, the cabling is irregular with this setup. Is this setup 
> hard to understand ? 
>
Not too hard once I realised how it needed to be arranged.

> One reason I haven't add this to the vs-manage-tiled-displays 
> tool is : I find it complicated to explain !
> Any hints w.r.t explaining this would be useful.
>
You're arranging the blocks in rows and disabling the right-most output of each row -  explaining it like that should help . . . but I've spent the whole evening trying to think of a good concise way to explain it, and so far nothing. I'll think about it some more and see if I can suggest anything, but it really is quite hard to explain clearly.

> > Thanks for implementing this so quickly!
> 
> As I said, this turned out to be fairly simple in the end. 
> The same mechanism works with QuadroPlexes too, but nobody 
> seems to be using more than one QuadroPlex at the moment with 
> VizStack. And now others can use this too.
> 
It's definitely a very nice feature. 

One question: is it possible (or meaningful) to use a value of [None,1] or similar? It seems like it would disable the first output on the GPU rather than the second, which might be useful in some cases . . .

Also, does it /have/ to be the last GPU in the row? It might be nice to be able to set up, say, a 5x5 display with the odd monitor in each row being in the middle. Obviously very low priority, but still possibly useful. Also, how hard would it be to support arbitrary mixing of different types of blocks? We have a 5x5 system (completely unrelated to the stuff I'm working on right now - it uses CGLX as the display system) which has the fifth column made up of two vertical pairs and a singleton, with the rest of the display made up of horizontal pairs - as it stands I think Vizstack would have to have the whole fifth column made up of singleton monitors. In practice it's probably not an issue, but if supporting arbitrary mixes of blocks is easy it might be something to consider for a future version.

And one final question: if you have a single GPU with four outputs, would you have to make each block 4x1, or could you make them 2x2? i.e. to get a 3x2 display would you need to have two rows of 4x1 blocks, or could you use one row of 2x2 blocks? I doubt there's any hardware out there where this would be an issue, but I imagine there's stuff on the horizon . . .

Lots of extra questions - none of them very critical for us, since with this update you've resolved the last outstanding issue we had.

Thanks,

Simon
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