[Mesa-dev] [PATCH 3/7] i965/fs: Use the sampler for FS pull constant loading on Ivybridge.

[Kenneth Graunke]

On 09/19/2012 03:10 PM, Paul Berry wrote:
> On 19 September 2012 13:27, Kenneth Graunke <kenneth at whitecape.org
> <mailto:kenneth at whitecape.org>> wrote:
> 
>     Data port reads are absurdly slow on Ivybridge due to cache issues.
> 
>     The LD message ignores the sampler unit index and SAMPLER_STATE pointer,
>     instead relying on hard-wired default state.  Thus, there's no need to
>     worry about running out of sampler units or providing SAMPLER_STATE;
>     this small patch should be all that's required.
> 
>     NOTE: This is a candidate for all release branches.
> 
> 
> Given that this affects only performance and not correctness, I'm having
> trouble convincing myself that this patch should be a candidate for
> release branches.  Don't we usually try to restrict release cherry-picks
> to things like rendering issues and avoiding GPU hangs?

Occasionally we pick performance work too, as long as it's not terribly
invasive or likely to cause problems.  Usually not, but if it's
important enough.

We cherry-picked the equivalent patch for the VS last time because it
was a /massive/ difference in performance.

I really only expect it to go to 9.0, but somebody could put it on 8.0
if there was a need for it.