Wed, 11 May 2005
So, yesterday, the extra PCI video card I ordered arrived at work for my work desktop.. Ahh! so he's going to do dual-head you say. NO! Triple head actually.. :) And I oh so very much like it.. It's a damn shame I can't have this at home.
The new card happens to be an nVidia GF2 MX400. Having two cards, means that doing what's called "TwinView" on the first is no longer possible. Basically the nvidia driver would present a nice wide display to the X server, where in actual fact the driver internally is telling the card to use both outputs. As opposed to the X server actually knowing that there's more than one head being used.
Now, I have the X server knowing about all three heads, and running the Xinerama extension. Before, the nvidia driver was using it's internal Xinerama extension, which meant that to the X server, this one really big display was split in two.
I don't know how the X internals work, but I'd imagine that the configuration now, will have the X server copying between the different video memories when you drag windows between the heads. Whereas before, as one big display, it was only one video memory to X.. Obviously, there's a performance hit here. You notice it for sure, when you drag a really huge firefox window between the heads. Small windows are hardly affected.
Now, 3 Heads, or speedy window drags between heads? I'm willing to take that trade off :)