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Old 03-13-06, 11:56 PM   #13
_john_i_
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Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by netllama
There's no need to send anything to linux-bugs@nvidia.com, as the same people who respond to linux-bugs respond here (including me).

I don't see anything in this thread to suggest that this is an nvidia driver bug. This sounds like a KDE bug, especially if its not present anywhere but in KDE/qt based applications. If I run a konsole and gnome-terminal side by side, with the same font, and dmesg in an infinite while loop, there is noticable and significant lag only in the konsole window. If there was a driver bug, I'd expect both windows to exhibit the same latency.

Has anyone submitted a bug to the KDE developers?

Thanks,
Lonni


Lonni,

The reason I suspect a driver bug is this doesn't seem to affect other nvidia cards. Just the 6600 series as far as I've been able to determine. I can put my old geforce 3, 4, and fx5200, and they all work perfectly in the same machine on the same installation. I put my FX6600GT back in, and it is slow again.

This is only when using color subpixel font antialiasing. If I turn off subpixel and use grey antialiasing, it runs fast. As far as the KDE/QT software is concerned, it doesn't know what it is sending the fonts to, it just passes the rendering down to the X libraries, and X down to the driver.

One thing to note is that a change made in the prerelease xorg fixed it temporarily, but broke binary compatibility. Aaron p. from nvidia then submitted a patch to restore binary compatability, which slowed it back down again. Come to find out though, before Aaron's patch, KDE/QT was rendering in grey instead of true color sub-pixel, so it just "appeared" fixed at first glance. Maybe this will point in the direction of the problem.

There has to be something wrong between QT/X/Nvidia driver communication for this specific card.

If you want to duplicate it yourself, use an AGP (don't know if PCIE is affected) version of the 6600gt, and in the KDE control panel under fonts/antialias configuration, click "use sub-pixel hinting". Log out of KDE and log back in after changing this setting. Then bring up a konqueror window on "slashdot.org", and watch konqueror render it slowly, and then drag a konqueror window across the web browser. It will be REALLY slow redrawing it.

If you can't duplicate it, I can shoot a video of it on my monitor with/without the subpixel rendering so you can see it.


BTW, I did post a KDE bug, but never got any response. I'm sure they took one look and blamed it on X or driver.

John
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Old 03-14-06, 10:34 AM   #14
netllama
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Default Re: Slow AA text rendering in KDE

John,
I've received a few reports of this problem from different people. The interesting thing is that some of the reports state that the problem is only present in NV4x GPUs (GeForce 6600, etc), while others state its only present before NV4x GPUs (geforce 3, 4, and fx5200, etc). In my testing, its present in every GPU, but only in Qt based applications (such as konsole, Konkie, etc). Using Gtk based applications with sub-pixel hinting and AA fonts never reproduces it for me. I'm not saying that this isn't an X or driver bug, however all the current evidence points to a KDE problem.

Can you point me to the KDE bug that you submitted for this problem?

Thanks,
Lonni
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Old 03-14-06, 10:59 AM   #15
ViRgiLiO
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Default Re: Slow AA text rendering in KDE

I'm an owner of a 6600GT card and I have the same problem here in KDE.
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Old 03-14-06, 03:36 PM   #16
_john_i_
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Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by netllama

Can you point me to the KDE bug that you submitted for this problem?

Here's the bug I submitted back in June. No one looked at it. Unfortunately, in November I closed it as resolved because the pre-release xorg 6.9 appeared to have fixed it. It was really a binary compatibility problem (Aaron's patch I mentioned earlier) that was doing gray rendering in QT/KDE apps (but not GTK oddly). The bug has to be somewhere in this neighborhood.

http://bugs.kde.org/show_bug.cgi?id=107690

I'll see if I can reopen it, or submit another.
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Old 03-14-06, 04:58 PM   #17
_john_i_
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Default Re: Slow AA text rendering in KDE

I was able to reopen the KDE bug report, so hopefully one of the KDE guys might take a look at it.
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Old 03-14-06, 08:08 PM   #18
donaldblanton
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Default Re: Slow AA text rendering in KDE

i had same problem and turned Kat off and it helped a lot still jerky at times but definatly an improvment.
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Old 03-14-06, 10:53 PM   #19
_john_i_
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Default Re: Slow AA text rendering in KDE

Lonnie,

After reopening the KDE bug, here is the response from KDE:

------- Additional Comments From mueller kde org 2006-03-14 23:59 -------
you're using the nvidia driver, right? then complain to nvidia ;(



Not very helpful. Too bad the developers are unwilling to look any farther when they hear proprietary drivers are in the mix.


donaldblanton: What is "Kat" ? I'm pretty sure it isn't something I am using.
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Old 03-15-06, 02:11 AM   #20
Linuxhippy
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Default Re: Slow AA text rendering in KDE

I decided to open this thread when I saw someone complaining at the forums at www.heise.de about this problem.
I have a PCIe-card (6600) so this problem seems not to be AGP specific.
btw. here we go: http://www.nvnews.net/vbulletin/showthread.php?t=44317

If I plug my FX5200 in instead everything is fast and smooth - and that is what I do since as programmer I need fast glyph bliting.
I also guess this has nothing to do with QT since it just happens with a small series of Nvidia chipsets, all the time is eaten by Xorg.
Why is it sooo hard to look into it - when reading your changelogs I see tons of fixes in the drivers for broken code in games. This is serious 2d stuff and "we" have to battle against nvidia devs that this is really a driver bug.

lg Clemens
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Old 03-15-06, 08:38 AM   #21
Ewald
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Default Re: Slow AA text rendering in KDE

I've a PCIe 6600 card and and have the same slow text scrolling as the other posters. KDE is 3.4.2 from Mandriva 2006. It happens also with grayscale (no subpixel) AA for me.

The problem does not occur with Radeon 9600XT or Matrox G400 cards. In fact I would prefer the good old Matrox right now!
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Old 03-15-06, 08:46 AM   #22
Ewald
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Default Re: Slow AA text rendering in KDE

'Kat' is a search utility like Google Desktop. It does make the system slower
but is otherwise totally unrelated to the problem at hand.
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Old 03-16-06, 06:24 AM   #23
d13f00l
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Default Re: Slow AA text rendering in KDE

Same here. Hmm. It doesn't seem to be half as bad with GTK apps! WEIRD!
Does subpixel hinting WORK in GTK apps?

Edit: Yeah. Huh. What on earth...

Last edited by d13f00l; 03-16-06 at 06:36 AM.
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Old 03-16-06, 09:31 AM   #24
Linuxhippy
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Default Re: Slow AA text rendering in KDE

another person having this problem: http://www.nvnews.net/vbulletin/showthread.php?t=66468
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