Transparent themes without composition

David Nolden zwabel at
Sun May 3 13:08:34 CEST 2009

Am Sonntag 03 Mai 2009 03:53:15 schrieb Zack Rusin:
> So first you don't even have the time to check the name of the hardware
> you're referring to (Intel doesn't have a GMA with number 955), then you
> make a completely bogus statement (even the very first initial GMA 900 had
> were fully capable of doing fully composited desktops), and you top it off
> with a sissy fit saying you've got no interest discussing it? Classy.
You're forcing me into a discussion I simply don't want to lead. It's not 
interesting to me, since I'm talking about present and near future problems, 
and not about a hypothetical far future.

Yeah then it's probably intel GMA 900, I don't have that notebook with me 
right now, I've bought a new one. One of the reasons was because I wanted to 
run KDE4 with composition nicely. But even with this NVIDIA 9600 GT, it 
doesn't run as good as without compositon, and I'm simply tired of this game.

> I like math. Wanna do math? Lets do math!
> Lets take the oldest Intel GMA, the 900.
> The 900 operates at peak of 330MHz, 4 pixels in a clock cycle.
> Therefore peak fill rate is: 330000000*4 = 1332000000 pixels per second
> Lets say you have 1600x1200 resolution and your composition manager wants
> to do animation at 60fps, therefore:
> 1600*1200*60 = 115200000 pixels per second
> So to do 1600x1200 at 60 frames per second our GPU needs to be able to push
> 115200000 pixels per second.
> GMA can do 1332000000, therefore: 1332000000/115200000 = ~11.5
> GMA 900 can work on 10x as many pixels as would be required!
> Even if you don't use the builtin blending unit and blend in shaders
> directly and assume the worst case scenario of sampling from 2 surfaces
> (aka, operate on 2 pixels per clock) and do something crazy in your shader
> you're still well within 30-60fps, even for really funky effects.

Anyway this certainly looks like one of those bogus math formulas that in 
earlier days used to tell me that my graphics card could do 20 million 
polygons per second, completely ignoring that the polygons also needed to be 
filled with textures, blitted to screen, synchronized to vsync, and whatever 
else (In the case of GMA 900 the memory is shared, so the textures are 
probably the main bottleneck, and for composition they are very large). In 
practice that card did max. 200 thousand real polygons per second.

If you think gallium will rescue me then first finish it, and then come back 
discussing with me.

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