[Mesa-dev] [PATCH] intel: Use a CPU map of the batch on LLC-sharing architectures.

[Kenneth Graunke]

On 01/20/2013 02:59 PM, Eric Anholt wrote:
> Before, we were keeping a CPU-only buffer to accumulate the batchbuffer in,
> which was an improvement over mapping the batch through the GTT directly
> (since any readback or other failure to stream through write combining
> correctly would hurt).  However, on LLC-sharing architectures we can do better
> by mapping the batch directly, which reduces the cache footprint of the
> application since we no longer have this extra copy of a batchbuffer around.
>
> Improves performance of GLBenchmark 2.1 offscreen on IVB by 3.5% +/- 0.4%
> (n=21).  Improves Lightsmark performance by 1.1 +/- 0.1% (n=76).  Improves
> cairo-gl performance by 1.9% +/- 1.4% (n=57).
>
> No statistically significant difference in GLB2.1 on SNB (n=37).  Improves
> cairo-gl performance by 2.1% +/- 0.1% (n=278).

Looks good to me.  Have you tested this on a non-LLC machine?

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>