[Mesa-dev] [PATCH] i965/fs: Disable opt_sampler_eot for more message types

[Matt Turner]

On Tue, Oct 20, 2015 at 2:56 AM, Neil Roberts <neil at linux.intel.com> wrote:
> In bfdae9149e0 I disabled the opt_sampler_eot optimisation for TG4
> message types because I found by experimentation that it doesn't work.
> I wrote in the comment that I couldn't find any documentation for this
> problem. However I've now found the documentation and it has
> additional restrictions on further message types so this patch updates
> the comment and adds the others.
> ---
>
> That paragraph in the spec also mentions further restrictions that we
> should probably worry about like that the shader shouldn't combine
> this optimisation with any other render target data port read/writes.
>
> It also has a fairly pessimistic note saying the optimisation is only
> really good for large polygons in a GUI-like workload. I wonder
> whether we should be doing some more benchmarking to decide whether
> it's really a good idea to enable this as a general optimisation even
> for games.

That's frustrating. I wish the documentation would contain notes like
this from the beginning, but maybe I should just be thankful that it
includes that text at all.

Both patches are

Reviewed-by: Matt Turner <mattst88 at gmail.com>