Request for help/advice in investigation of one interesting "huge FPS regression" bug

Alexey Loukianov mooroon2 at mail.ru
Sat Apr 14 22:22:34 CDT 2012


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Good day to all.

Henri, Stefan, I address this message to you at the first place as to a main
developers of wined3d/opengl stuff. Nevertheless, hints and help are welcome
from anyone, cause ATM I'm totally confused and don't know what else to try to
investigate a case.

What I've got here is an app (localized version of "Perfect World" MMORPG game
client from "Mail.Ru Games Corp") that seems to suffer huge FPS regression
which I believe to be a bug in nVIDIA drivers rather than a regression in Wine.

Details are following.

When I configure an app to run in a windowed mode I've got around 40 FPS on
game login screen with nVIDIA drivers 275.09.07, but switching into using more
recent versions causes FPS to drop to around ~10. Configuring the game to use
fullscreen more fixes the issue - I've got ~30-40 FPS at game login screen no
matter the driver version I use.

I've been suspecting that this issue might be related to vsync control (and a
recent change in nVIDIA linux drivers for vsync to be on by default) that
causes the issue, so I had exported __GL_SYNC_TO_VBLANK="0" into the
environment and used nvidia-settings to set vsync to be off by default. Using
a small native opengl demo program I had specifically written to test for
vsync state I can prove that vsync defaults to be off on my system. Also I had
modified Wine's winex11.drv opengl.c in a way that a call to
wglSwapIntervalEXT always sets swap_interval to be zero, no matter what was
originally requested. Nevertheless, I still got this strange FPS drop when I
run the game in a windowed more with a recent nVIDIA drivers.

What could be a cause for it? What I want is to track down the problem to it's
roots and check if it's really a bug in nVIDIA drivers. In the end I would
like to implement a small opengl demo that would trigger the bug so nVIDIA
wouldn't be able to reject my bug report on a matter that "it's a Wine bug,
prove us that it's not".

- -- 
Best regards,
Alexey Loukianov                          mailto:mooroon2 at mail.ru
System Engineer,                            Mob.:+7(926)218-1320
*nix Specialist

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