[Bug 103343] [GEN9+] 2-6% performance drop in GfxBench ALU2 & SynMark TexFilterTri from "i965/tex: Use blorp texture upload for all CCS_E textures"

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=103343

--- Comment #1 from Eero Tamminen <eero.t.tamminen at intel.com> ---
TexFilterTri trilinear filtering regression is more mysterious of the two.

This simple test is fully memory bandwidth bound and its 256x256 RGBA8 textures
are almost completely black (one edge just has stripe or two) i.e. they should
compress very well with CCS_E.  Test does several similar draw calls, with
shader sampling 8 textures which have 8 mipmap levels, down to 1x1 size.

Each of the mipmap levels is separately uploaded with glTexImage2D().  I tried
skipping the blorp usage for smaller levels, but that didn't change anything,
only skipping blorp usage for all the levels for these 256x256 textures gets
the  regression to go away.  I.e. issue isn't related to texture / mipmap level
sizes.

The full texture settings are:
- type: TEXTURE_2D / RGBA8 / UNSIGNED_BYTE
- level 0: 256x256
- level 8: 1x1
- GL_TEXTURE_MAX_LEVEL = 8
- GL_TEXTURE_MIN_FILTER = GL_LINEAR_MIPMAP_LINEAR
- GL_TEXTURE_MAG_FILTER = GL_LINEAR
- GL_TEXTURE_WRAP_S = GL_REPEAT
- GL_TEXTURE_WRAP_T = GL_REPEAT


ALU2 test is partly GPU ALU, partly memory bandwidth bound.  Its textures won't
compress as well as TexFilterTri ones should, and they're larger, with
following formats:
* TEXTURE_2D / DEPTH_COMPONENT / UNSIGNED_INT:
  - size: 1920x1080 (8100 kiB)
* TEXTURE_2D / DEPTH_COMPONENT24:
  - size: 1920x1080 (2025 kiB)
* TEXTURE_2D / RGBA / UNSIGNED_BYTE:
  - max level: 0
  - min size: 256x256 (256 kiB)
  - max size: 1920x1080 (8100 kiB)
* TEXTURE_2D / RGBA8:
  - max level: 1
  - min size: 256x256 (256 kiB)
  - max size: 1920x1080 (8100 kiB)

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