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

[Alexey Loukianov]

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15.04.2012 21:50, Stefan Dösinger wrote:
> It could also be because of some additional features added in newer
> drivers. 16 byte alignment for vertex buffers is a possibility, I believe
> it was added in the 280 drivers. You can check this by disabling
> GL_ARB_map_buffer_range.

This one isn't the case, as the problem affects ancient versions of Wine that
don't use this extension, like 1.2.3 (under which the app in question actually
performs much better comparing to fresher releases).

Actually I've got a small patchset here against 1.5.2 which is required to
bring the FPS levels for this game to a way it was with 1.2.3, and one of the
patches from this patchset effectively disables GL_ARB_map_buffer_range usage.
So, yeah, GL_ARB_map_buffer_range is causing trouble for this game, but it is
not the one to blame for the issue I'm trying to resolve.

Meanwhile I've been able to reproduce this bug on another PC I've got here at
home. It was originally spotted on a box having 8GB DDR3 RAM, GeForce GTX 550
Ti with 1GB and AMD FX 8120 CPU running Fedora 14-based LFS-like system with
32bit PAE-enabled kernel. The system I've been able to reproduce the bug on is
a box equipped with AMD Phenom II x4 955 CPU, 8GB DDR2 RAM, GeForce 8600 GT
with 256MB VRAM running Linux Mint 9 with 32bit PAE-enabled kernel 3.0.0-16.
Unfortunately I haven't got access to any system with ATI/AMD card a.t.m., but
chances are I would be able to lay my hands on one with AMD A8 CPU with
integraded Radeon card. It would be interesting to check if this bug affects
ATI/AMD.

Thanks for oprofile hint, but unfortunately I haven't got any experience with
it. I also been thinking about trying to use APITrace, but I don't have any
experience with it either and I don't know if it's compatible with non-OSS GPU
drivers.

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

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