[Mesa-dev] Gallium optimization: add the user pointer into pipe_vertex_buffer and pipe_index_buffer

[Marek Olšák]

Hi,

does lack of feedback mean that this idea is still off the table
despite the performance increase, or that nobody is opposed to it
anymore?

In other words, may I start adapting the other drivers and send patches?

Thanks,
Marek

On Thu, Apr 12, 2012 at 8:08 PM, Marek Olšák <maraeo at gmail.com> wrote:
> Hi,
>
> In parallel with my other work, I have been looking for ways to
> decrease our draw-call overhead and tried adding the user buffer
> pointer into pipe_vertex_buffer and pipe_index_buffer, which led to a
> removal of a lot of code from st_draw.c. With that change, I have
> tested r300g with torcs and ipers and got surprising results.
>
> Pros:
> - 9% performance increase in torcs (open source game)
> - 6% performance increase in ipers (from Mesa demos)
> - Besides that, a little over 110 lines of code was removed from st_draw.c.
>
> Cons:
> - The user buffer contents are fully mutable between draw calls,
> however drivers should be ready for that now.
>
> I know this was brought up long ago and it was NAK'd, but you know,
> it's really hard to resist this framerate-increasing "cleanup". I
> guess many people would agree.
>
> Here's the proof-of-concept implementation (2 commits):
> http://cgit.freedesktop.org/~mareko/mesa/commit/?h=gallium-user-ptr-in-states&id=21cf1414df5e24942fe4f0fdab008c9b3bc63802
> http://cgit.freedesktop.org/~mareko/mesa/commit/?h=gallium-user-ptr-in-states&id=a582f05b56b89e8c2e1345b6c2b6eb9663919eba
>
> Here are the exact benchmark results:
>
> Torcs before:
> libGL: FPS = 22.3
> libGL: FPS = 21.6
> libGL: FPS = 20.5
> libGL: FPS = 20.4
>
> Torcs after:
> libGL: FPS = 24.4
> libGL: FPS = 23.7
> libGL: FPS = 22.2
> libGL: FPS = 22.0
>
> Ipers before:
> Frame rate: 30.212976
> Frame rate: 30.183079
> Frame rate: 30.183079
> Frame rate: 30.257936
>
> Ipers after:
> Frame rate: 31.761785
> Frame rate: 32.000000
> Frame rate: 32.082922
> Frame rate: 32.146389
>
> Comments welcome.
>
> Thanks,
> Marek