[Intel-gfx] [PATCH] drm/i915: Update MOCS settings for gen 9

[Arkadiusz Hiler]

On Wed, Apr 26, 2017 at 06:00:41PM +0300, David Weinehall wrote:
> Add a bunch of MOCS entries for gen 9 that were missing from intel_mocs.
> Some of these are used by media-sdk; if these entries are missing
> the default will instead be to do everything uncached.
> 
> This patch improves media-sdk performance with up to 60%
> with the (admittedly synthetic) benchmarks we use in our nightly
> testing, without regressing any other benchmarks.

Hey David,

I am testing some of the extended MOCS with Mesa and the differences I
see fit in the margins of statistical error.

Odd, I thought, so to make sure I haven't messed up anything in the
process of compiling, setting LD_LIBRARY_PATH and benchmarking I turned
everything to UNCACHED - and I saw severe performance drop.

So here is the question it induced:

Have you used the "closest neighbour" from entries available or did you
defaulted to the UNCACHED ones? That could be the culprit.

Note: I have tested MOCS for VB and Render Target only, and only in a
few synthetic cases - it will require much more fine-tuning and
benchmarking before any final conclusions.

-- 
Cheers,
Arek