> -----Original Message-----
> From: Keith Whitwell [mailto:[EMAIL PROTECTED]
> Sent: 2007年8月31日 18:27
> To: Nan hai Zou
> Cc: MESA-Devel
> Subject: Re: mesa: Changes to 'master'
>
> Nan hai Zou wrote:
> > src/mesa/drivers/dri/i965/brw_clip_line.c | 7 +
> > src/mesa/drivers/dri/i965/brw_clip_state.c | 2
> > src/mesa/drivers/dri/i965/brw_clip_tri.c | 105
> ++++++++++++++++++++++++++++-
> > src/mesa/drivers/dri/i965/brw_clip_util.c | 12 ---
> > 4 files changed, 112 insertions(+), 14 deletions(-)
> >
> > commit diffs at http://gitweb.freedesktop.org/?p=mesa/mesa.git;a=summary
> >
> > New commits:
> > commit b47c9f8c915ae4ca8c7fa5ee3b6b64f17c38b569
> > Author: Zou Nan hai <[EMAIL PROTECTED]>
> > Date: Fri Aug 31 13:42:20 2007 +0800
> >
> > optimize 965 clip
> > 1. increase clip thread number to 2
> > 2. do cliptest for -rhw
>
> Nan hai Zou,
>
> Isn't it the case that the hardware bug that requires the -rhw
> workaround is fixed in later versions of the hardware? It would be good
> to turn the workaround off in those cases - both in the clipper and the
> vertex shader.
>
> Likewise, the various workarounds for send destination dependency
> checking (eg. in brw_vs_emit.c emit_math1(), etc.) can be turned off in
> later revisions and steppings of the hardware. This is probably quite
> important as I believe the workaround defeats built in latency-hiding
> characteristics of the hardware.
>
> It's also worth noting that the hardware support for guard band clipping
> isn't turned on in the current i965 driver. Making use of this could
> give a good boost to clipping performance...
>
> Otherwise, looking good. It's nice to see the driver continuing to evolve.
>
> Keith
Hi Keith,
Yes it is for the -rhw workaround. It just do a fast clip test before
the relatively slower full clip when -rhw workaround is needed.
I am testing the 965 driver performance with some 3D engines,
I see clipper take a lot of GPU time with Doom III demo and becoming a
bottleneck.
I guess it is because the heavily used stencil shadow algorithm in
Doom3 III engine, because it is very likely shadow volumes get clipped than
normal scenes.
For other game engines, I don't see clipper becoming a bottleneck maybe
because they are not using stencil shadow. Although the stencil shadow does not
look work quite correct on DOOM 3 demo, I think it is still worth to optimize
the clipper..., later I will fix the 3D effect issue.
Actually this change for -rhw does not optimize the clip performance in
DOOM III too much. I have only got around 20% speed-up with cliptest on -rhw.
Another change clip thread number to 2 in this patch gives another more than
50% speed up.
I have tried guard band method, not seeing any performance gain with Doom
III...
I will continue checking the 3D pipeline to try to speed up the driver
performance.
Thanks
Zou Nan hai
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