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Old 08-16-05, 08:10 AM   #1
antoni
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Default glxgears at double speed

Hi !
I have a FX5300 chip card, in Debian Sarge AMD64 system with 2.6.11 Kernel
After correct installation of drivers and editing XF86Config-4 file
the gears in "glxgears" application turn at double speed that usual
I have also halved FPS (3500 fps)

Someone can help me? Thanks!!!
P.S. also xmms's Opengl Spectrum Analizer Plugin turn too fast...
.
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Old 08-16-05, 08:18 AM   #2
debian_penguin
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Default Re: glxgears at double speed

Well, usually you don't need that much FPS, an ordinary screen goes up to 85 Hz, so you don't need more. It's just an index of how much your card "could" do...

Try setting Sync to VBlank to "on" with nvidia-settings. Don't be scared if glxgears drops down to 80 fps, it's just as it should be, you won't have any performance change for the rest of the graphics applications. Some old GL-based programs don't sync with the display refresh rate and give anomalous high fps.

You can also set up the ambient variable "__GL_SYNC_TO_VBLANK" to 1 to obtain the same effect on application launched from command-line without setting it globally as nvidia-settings do.

Good luck,

d_p
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Old 08-16-05, 11:45 AM   #3
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Default Re: glxgears at double speed

Perfect
Thanks!
I use my LCD at "only" 1024x768 @ 60 Hz , and with sync to vblanc "ON", I obtain just 60 fps

$ __GL_SYNC_TO_VBLANK=1 glxgears
300 frames in 5.0 seconds = 60.000 FPS
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Old 08-16-05, 02:09 PM   #4
evilghost
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Default Re: glxgears at double speed

This is good to know, thanks, but doesn't VSYNC produce laggy move movement in gaming?
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Old 08-16-05, 06:45 PM   #5
ZicoTheTux
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Default Re: glxgears at double speed

On the contrary.
It IS correct, thar VSYNC slows down your FPS BUT only to that limit as your refresh rate.
If you have 75Hz, your FPS reaches max 75 and stay there (if possible).
If you have more than 75 on a 75Hz Monitor the screen may flicker.
Example:
Imagine a flickering Light Source (screen turns black and white - simple example) in Doom3 or Ut2k4. If your FPS is at 90 and ou have only 75Hz, you Monitor can only show 75 Images per Second but the Game produces 90. This could lead to the scene, that the half of you screen shows a light picture, and the rest of it a black.
That counts for movements, too. Imagine an enemy in a game and this enemy moves very fast from left to right. Same effect The "upper part" of the enemy is more on the right, thn the left.. see NOT in sync... VSYNC prevent this kind of effects.
For sure, you get more worse FPS in benchmarks, but every FPS rate, that is higher than your refresh rate is useless, needs more GPU/CPU Power and could lead to this events described...
Of cource VSYNC is useless in Games where you never reach high FPS like Doom3 where the FPS rates are restricted to 60 and on much systems much lower
But it should NEVER cause laggy gameplay.

Sorry for this bad english, but i hope i described it a little bit...
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Old 08-16-05, 10:15 PM   #6
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Default Re: glxgears at double speed

Thanks for the explanation, but let me explain a bit more. I've always heard, and at times seen, mouse movement in FPS games not being instant with VSYNC enabled. I've also heard that you will always see this effect with VSYNC enabled unless you are also using Triple Buffering. It's almost a 25ms to 250ms latency lag on the time the mouse movement is made until the time it is received/rendered on the screen.

Does this make sense? I understand that it doesn't affect framerate other than to set a ceiling limit on rendering speed to not exceed the vertical refresh rate of the monitor, but the mouse-lag is an issue I did have in the Win32 world.

I hope this makes sense.
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Old 08-17-05, 03:03 AM   #7
debian_penguin
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Default Re: glxgears at double speed

Hi all,

evilghost, you're right: in some situations I've experimented on some friend's machines, syncing to vBlanking (although diminishing the CPU charge and RAM usage quite a bit) used to cause uncontrollable mouse movements. It happened mainly in games such as Quake 3 Arena and other few 3d shooters when rendering a bit more elaborate light effects than usual. But it was also (if I'm not wrong) found on ATI based cards, rather than NVIDIA ones. I've never had this problem, even if I'm one of the "X frozen but movable mouse" ones.

I don't have a clear idea in mind on what is the role of the graphics card in the interaction mouse-bus-screen, in my "dream world" I'd guess they be somehow independent. Even though I understand that a graphics hardware mouse handling might be better performing than a software one.

However, with vsync enabled (I have only a Geforce4 440 Go 64M on a laptop), I get smoother and more "solid-looking" 3d applications on the LCD screen.

If anyone has an idea on what exactly the graphics card does in an X-server ambient, please let us know, I'm quite curious about it


Thank you!

d_p
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Old 08-17-05, 03:24 AM   #8
ZicoTheTux
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Default Re: glxgears at double speed

In the most situations it shoudn't affect the gameplay.
But first ... try to test VSYNC with games that run veeery smooth on your system. You see, as far as i know, VSYNC needs some extra power, too TO slow down the FPS to the sync rate. in one case or another or in very hardware intense games - like doom3 - where you try to reach 30 or 40 FPS it could struggle the gameplay because the game tries to speed up and the mouse is most directly affected by the FPS. it's hard to explain in non-german for me

See, in games that demandy my hardware often to 100% i leave it off.... but in CS, UT, UT2k4 i always have it enabled. UT looks much more better with it because it will not run on 200 FPS anymore...
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Old 08-17-05, 08:25 AM   #9
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Default Re: glxgears at double speed

Thanks guys, this is exactly what I was trying to get at. As debian_penguin hinted, I did have an ATI card when I was living in the dark and gloomy Win32 world. This thread turned me on because I can easily see how rendering a framerate faster than your monitor can draw it isn't ideal. My monitor runs 1280x1024@100Hz, so I'll at least pull 100FPS in UT2004, which often times runs +150FPS.

Thanks everyone for all the replies, additional information, and suggestions. This was exactly what I was looking for and I appreciate all the contributions.

ZicoTheTux, your english was perfect and I understood exactly what you meant.

Tonight, I'll set Sync to VBlank to "on"
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