Go Back   nV News Forums > Linux Support Forums > NVIDIA Linux

Newegg Daily Deals

Reply
 
Thread Tools
Old 07-24-06, 02:11 AM   #109
brewt
Registered User
 
Join Date: Dec 2005
Posts: 7
Default Re: Slow AA text rendering in KDE

Does anyone still have the qtperf source code (the link isn't working for me)? I'm trying to figure out where sub-pixel rendering is slow. I loaded a file in kwrite, checked that it was doing sub-pixel rendering and scrolling and redrawing seemed pretty decent on my system (A64 X2 3800+, 6200 PCI-E).
brewt is offline   Reply With Quote
Old 07-24-06, 02:45 AM   #110
firephoto
Registered User
 
Join Date: Aug 2004
Posts: 7
Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by brewt
Does anyone still have the qtperf source code (the link isn't working for me)? I'm trying to figure out where sub-pixel rendering is slow. I loaded a file in kwrite, checked that it was doing sub-pixel rendering and scrolling and redrawing seemed pretty decent on my system (A64 X2 3800+, 6200 PCI-E).
The scrolling and redrawing is actually fine if your system specs are pretty good (which yours are), the problem is that scrolling or any kind of moving/redrawing eats up the cpu so if something else is going on that actually needs the cpu then one or the other is going to get affected. I never really notice a performance hit, what I notice is the cpu temp going up and the fan noise along with it while the vid card temps stay at their normal (high) temps.

The trolltech/kde problem theory is a bit comical too. Of course they should fix what's obviously their problem that only affects one hardware vendors cards of certain models with certain drivers... so obvious.
firephoto is offline   Reply With Quote
Old 07-24-06, 06:47 PM   #111
d13f00l
Registered User
 
Join Date: Apr 2005
Posts: 197
Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by firephoto
The scrolling and redrawing is actually fine if your system specs are pretty good (which yours are), the problem is that scrolling or any kind of moving/redrawing eats up the cpu so if something else is going on that actually needs the cpu then one or the other is going to get affected. I never really notice a performance hit, what I notice is the cpu temp going up and the fan noise along with it while the vid card temps stay at their normal (high) temps.

The trolltech/kde problem theory is a bit comical too. Of course they should fix what's obviously their problem that only affects one hardware vendors cards of certain models with certain drivers... so obvious.
_NO_

Some KDE applications are affected, not all. KEdit is fine, KWrite is not. It happens with all drivers to some degree, except really old Nvidia drivers that wern't slow because they rendered the text improperly. GTK apps are much better in terms of CPU usage when subpixel hinting on.

It's _MOSTLY_ a KDE issue. But right, people with faster PCs won't notice the issue.
d13f00l is offline   Reply With Quote
Old 07-24-06, 07:10 PM   #112
d13f00l
Registered User
 
Join Date: Apr 2005
Posts: 197
Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by Linuxhippy
My question:
But then why does a FX5200 outperform a GF6600 powered system with a much faster CPU by a factor of 2?
Have there been some regressions in chip-design which cause this slowdown?

Answer:
It has to do with bus access patterns. I'm afraid I can't go into a lot of detail.
If PCIE cards really are slower in KDE, that's terrible. Maybe AGP cards are better at doing a bunch of tiny little sysram to vram transfers than PCIE? I guess you could call that a hardware regression. That's just another compounding problem though ontop of the main problem that KDE apps are just broken in general.
d13f00l is offline   Reply With Quote
Old 07-25-06, 01:56 AM   #113
Linuxhippy
Registered User
 
Join Date: Feb 2004
Posts: 585
Default Re: Slow AA text rendering in KDE

Quote:
Some KDE applications are affected, not all. KEdit is fine, KWrite is not. It happens with all drivers to some degree, except really old Nvidia drivers that wern't slow because they rendered the text improperly. GTK apps are much better in terms of CPU usage when subpixel hinting on.
All apps are affected which draw glyphs via subpixel-aa to native surfaces (screen, pixmaps). No matter wether you use gtk, xlib or qt. About 4 months ago I wrote microbenchmarks.
But however since I assume you can't code (really well) ... you just have to trust me.

Quote:
that KDE apps are just broken in general.
Ah yep - broken in general. How could I've missed that ;-)
Man you're .... ****** ;-)

Quote:
It's _MOSTLY_ a KDE issue. But right, people with faster PCs won't notice the issue.
I've an amd64 machine and it suffers a lot. Do you think I would scream that much if I would not notice the problems *lol*
Notice that readback performance stays quite the same no matter wether you own an sempron 2800+ or an athlon64 X2 5000.

Clemens
Linuxhippy is offline   Reply With Quote
Old 07-25-06, 09:40 PM   #114
gnutux
Linux User: 362616
 
Join Date: Oct 2005
Location: Toronto, Canada
Posts: 108
Default Re: Slow AA text rendering in KDE

funny, I have a NVIDIA GeForce 6600 (AGP) graphics card w/ the latest driver and I don't find having any AA text being rendered slowly and I use KDE/QT apps very often. Also, I can't find this problem on Konsole either.

This is indeed an odd problem.

gnutux
__________________
Specs: AsusTek P4B533-VM, Intel Pentium 4 2533MHz, 120 GB HDD Maxtor, 80 GB HDD WD, 1GB PC3200 RAM, NVIDIA GeForce 6600, openSUSE 10.2 (Main), MacOS X 10.4.5 (leisure use, backup)
gnutux is offline   Reply With Quote
Old 07-26-06, 05:28 AM   #115
d13f00l
Registered User
 
Join Date: Apr 2005
Posts: 197
Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by Linuxhippy
All apps are affected which draw glyphs via subpixel-aa to native surfaces (screen, pixmaps). No matter wether you use gtk, xlib or qt. About 4 months ago I wrote microbenchmarks.
But however since I assume you can't code (really well) ... you just have to trust me.
What does kedit draw to? It's totally fine, while kwrite is not.

Are the microbenchmarks you're referring to those QT programs that drew a string like 10,000 times and timed how long it took, or are you talking about something else? Also, didn't you say once that Java rendered subpixel hinted text much faster than QT or GTK?

Also, you have a A64 3400? I don't believe that's a dual core chip, as in, you only have one processor, while a multi-core Xeon computer would have several.

If an application used 100% cpu time, the person on the Xeon system would barely notice because their other CPUs are free, while your A64 would slow to a crawl.

You don't have an A64 X2, right?

An a64 in this case is not comparable to a Xeon system, the Xeon system will not be affected.


I'm not that familiar with QT or GTK, or X in general.

Naturally, subpixel hinted text rendering is going to be MUCH slower than any other kind of text rendering no matter how you look at it. My point is that only some KDE programs are actually slowed down to the point of unusability. If I drag a screen full of text around in kedit, my CPU usage might be at 40-50%, but that's fine. KWrite it will be at 100%.

What do you expect Nvidia to do? Their Xrender implementation isn't the best, but I don't think there's a performance-crushing bug in particular that's causing this. It happens with other cards, and it happens also on my Geforce 4 MX 440.

What are you suggesting? There doesn't seem to be any driver regressions anywhere. It works good in older drivers because it was brokenly HW accelerated, and now it's fixed and slowly done in software.

I could write an SDL program that does subpixel hinting in software if I _REALLY_ wanted, and I could make it run at several thousand frames a second by being efficient in my code.



Do you have a test app written in with XLib/XFT? That would be interesting to see if it was still slow.....maybe I will code one up tomorrow night. It can't be too hard...

Last edited by d13f00l; 07-26-06 at 05:42 AM.
d13f00l is offline   Reply With Quote
Old 07-26-06, 06:04 AM   #116
d13f00l
Registered User
 
Join Date: Apr 2005
Posts: 197
Default Re: Slow AA text rendering in KDE

I'm trying out gtkperf

Nvidia Driver: Subpixel Hinting off, no font hinting, or anything

1sec for GTKDrawingArea - Text test
Subpixel On
13Sec

Trying the Vesa driver now

1.5 GTKDrawingArea - Text test w/ subpixel off
2.5 with it on


Ok...Vesa is 2.5 vs Nvidia's 13s...nevermind

I'm an idiot, something obviously _IS_ wrong with the Nvidia driver, but I wonder what that is?



Just an idea, but do you know if GTK/QT/XFT does direct pixel manipulation in VRam to render fonts? Couldn't that cause speed issues? It'd be better to copy the entire thing to system ram first, then edit it, then upload it to the card.

Last edited by d13f00l; 07-26-06 at 06:20 AM.
d13f00l is offline   Reply With Quote

Old 07-26-06, 08:32 AM   #117
d4rk74m4
Registered User
 
Join Date: Aug 2004
Posts: 72
Default Re: Slow AA text rendering in KDE

Quote:
Originally Posted by d13f00l
Ok...Vesa is 2.5 vs Nvidia's 13s...nevermind

I'm an idiot, something obviously _IS_ wrong with the Nvidia driver, but I wonder what that is?
Well, there's probably not anything *wrong* with the driver as such. My guess is that the driver is falling back to software rendering, which would mean they need to pull data from video ram back into system ram (*slow*).

With vesa, the data is already in system ram obviously - so it'll be faster than an accelerated driver's software fallbacks anyday.
d4rk74m4 is offline   Reply With Quote
Old 07-26-06, 12:29 PM   #118
Linuxhippy
Registered User
 
Join Date: Feb 2004
Posts: 585
Default Re: Slow AA text rendering in KDE

Sorry if I don't answer all your questions ... but it does not lead to anything :-/

Quote:
What do you expect Nvidia to do? Their Xrender implementation isn't the best, but I don't think there's a performance-crushing bug in particular that's causing this. It happens with other cards, and it happens also on my Geforce 4 MX 440.
Do subpixel rendering using shaders on boards where they are available (FX5200 and up). This way they could also sell now hw to customers which really want this feature.
Sun showed that this can be done and that its quite fast on higher-level hw.

lg Clemens
Linuxhippy is offline   Reply With Quote
Old 01-11-07, 02:10 PM   #119
lastrainson
Gentoo user
 
Join Date: Jan 2007
Posts: 1
Default Re: Slow AA text rendering in KDE

little warm up for this thread. We are now in 2007 and I'm experiencing the very same issue (X eating all CPU time when rendering anti-alisased fonts + Very very very slow font rendering of course).
Hardware : ASUS A8JS laptop w/ a 7700 Go GPU. Drivers : 1.0-9746 .

It seems this issue has been kept unresolved for quite some time now... Excepted if some of you people found a workaround ? nVidia stated here that they would look into the problem some months ago but it seems nothing has changed regarding this problem...
lastrainson is offline   Reply With Quote
Old 01-25-07, 03:06 PM   #120
gmichels
Registered User
 
Join Date: May 2006
Posts: 8
Default Re: Slow AA text rendering in KDE

Yes, I've been using grey hinting on my 6600 Go for more than 6 months now. I just re-enabled RGB hinting and boy, it does look way better, but still way slower.

We're already on 9746 and still no fix for this?
gmichels is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fedora KDE 16 Geforce GTX260 and slow gtk applications Rendering NVIDIA Linux 10 07-11-13 08:02 AM
[GeForce 8800 GTS] 2D rendering regression (extreme slowdown) introduced with 295.49 Seb L. NVIDIA Linux 0 06-22-12 07:48 AM
Very slow X startup Jeremy NVIDIA Linux 96 05-23-03 11:11 AM
NVidia Display Drivers screw up KDE Webgraph NVIDIA Linux 11 10-08-02 09:57 PM
poor kde X windows performance after restart HeadStrong NVIDIA Linux 5 08-19-02 08:17 PM

All times are GMT -5. The time now is 04:58 AM.


Powered by vBulletin® Version 3.7.1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 1998 - 2014, nV News.