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Old 04-03-06, 10:14 PM   #65
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Join Date: Apr 2005
Posts: 197
Default Re: Slow AA text rendering in KDE

Originally Posted by Linuxhippy
It could be that moden nvidia cards use shaders for subpixel-aa rendering so this description only applies to cards which do the subpixel-stuff in software like (i am quite sure) my NV18.
Nope, even modern cards don't use shaders for AA rendering. I was talking to one of the devs about this, it would be a possibility, however.

I think, like you said earlier, the issue might be latency involved copying data from system ram to the video card's ram over the AGP bus repeatedly.

For example, I was programming a game before. Drawing 1200 16x16 tiles to the screen was _MUCH_ _MUCH_ slower than drawing a single 640x480 surface to the screen.

If kwrite renders stuff character by character, this would result in each character being rendered in software in the system ram, than transported across the AGP bus back and fourth. That right there would kill performance, while rendering everything in software would be just mildly slow.

I've given up on the issue, this issue, among other performance issues, won't be _totally_ resolved until X moves away from software rendering and accelerates everything in hardware

However, any hacks nvidia could do to improve the situation in the meantime would be _MUCH_ appreciated.

The KDE team seemingly refuses to look at the issue. The latest bug I had posted there was closed a couple days ago, and most of the devs say they won't bother if it's fixed in KDE/QT 4. Sad panda

All we can do is wait for the issue to resolve itself through coincidence, or through direct efforts of Nvidia although I'm curious as to how much they can speed it up, especially on older cards without freely available math coprocessors(shaders) to offload the work to.

Last edited by d13f00l; 04-03-06 at 10:25 PM.
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