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Old 04-23-06, 01:29 PM   #25
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Default Re: Gainward 7800 GS OC AGP 512MB - no faster than 6800 GT?

Hi monkfish, sorry to hear you're still having problems.

Did you attempt to check if v-sync is enabled? In nvidia-settings make sure in the opengl settings panel, that "sync to v-blank" is unchecked. Load doom3, type "com_showfps 1" in the console. Then watch the framerate counter while the timedemo runs. I mentioned in my last post how to detect if v-sync is active, your framerate will jump between precise dividers of your monitor's vertical refresh rate.

v-sync will seriously limit your framerates, and that looks the most likely cause of your problem at this point.

Failing that, i can only think of two things. With the current nvidia driver, if you use composite effects on your xserver (shadows, translucency) then opengl perofrmance is impacted. I don't know if this only affects windowed opengl or fullscreen apps too though. The second thing could be a kernel configuration problem, such as preempt. If your kernel is set to desktop preemption, try recompiling with server preemption, as that gives the cpu over the foreground task more completely. It'll prevent any other processes you might have running from interfering with doom3's cpu usage.

v-sync seems the most likely cause though, so check that out first.
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Old 04-23-06, 05:47 PM   #26
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Default Re: Gainward 7800 GS OC AGP 512MB - no faster than 6800 GT?

Hello chaps; me again.

I recompiled my kernel - twice, at freqs 250Hz and 100Hz - and turned off SMT (hyperthreading), pre-emption including big kernel lock.

At 250 Hz timedemo gave me (over 2 runs, as are the following) 48fps.
At 100 Hz timedemo gave me 53fps.

That's at 1024x768 with no AA. 53fps is still 10fps below my Windows benchmark.

[EDIT]I also turned off bump maps. There was NO DISCERNIBLE DIFFERENCE IN FRAMERATE!!!

Interestingly, at 1600x1200 with 2xbilinear AA I get 46fps.

Therefore with all the bits and pieces I can think of optimised out, I'm still 10fps below Windows. That's ~15% discrepancy - clearly something's still not right.

I checked v-sync and it's off. I also did com_showfps which showed fluid framerate changes - no jumps.

The only thing I can consider is that my software RAID is interfering somehow - but then everything's precached (timedemo demo1 cache).

Mysh - any ideas? nVidia - any ideas? Is it important that I a) can't enable fast writes and b) get this sound-related error from Doom3 (although can hear sound in game proper, but not in demo):


Thanks, as ever,


Last edited by MonkFish; 04-24-06 at 02:01 AM.
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Old 04-24-06, 05:35 AM   #27
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Default Re: Gainward 7800 GS OC AGP 512MB - no faster than 6800 GT?

After pondering the issue for a while, I think I know why Doom3 under Windows is so much faster than Linux.

It's SMP support, innit.

Doom3 for Windoze has SMP support, whereas it's Linux variant doesn't. Additionally, I understand, the nVidia Windoze driver has better SMP support as well, but that's probably not as crucial as Doom3 supporting SMP.

I would test the theory by removing one CPU, but I can't be bothered.

If anyone would disagree, please let me know!

Last edited by MonkFish; 04-26-06 at 07:49 AM.
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