• Ville Syrjälä's avatar
    drm/i915: Enable eLLC caching of display buffers for SKL+ · c0888e9e
    Ville Syrjälä authored
    Since SKL the eLLC has been sitting on the far side of the system
    agent, meaning the display engine can utilize it. Let's enable that.
    
    I chose WB for the caching mode, because my numbers are indicating
    that WT might actually be WB and WC might actually be UC. I'm not
    100% sure that is indeed the case but at least my simple rendercopy
    based benchmark didn't see any difference in performance.
    
    Also if I configure things to do LLCeLLC+WT I still get cache dirt
    on my screen, suggesting that is in fact operating in WB mode
    anyway. This is also the reason I had to fix the MOCS target cache
    to really say PTE rather than LLC+eLLC.
    Since SKL the eLLC has been sitting on the far side of the system agent,
    meaning the display engine can utilize it. Let's enable that.
    
    Eero's earlier benchmarks numbers:
    "* Results in GfxBench and Unigine (Valley/Heaven) tests were within daily
       variation on the tested SKL machines
    
     * SKL GT4e (128MB eLLC) / Wayland / Weston:
       +15-20% SynMark TexMem512 (512MB of textures)
       +4-6% SynMark TerrainFly*, CSCloth, ShMapVsm
       -5-10% SynMark TexMem128 (128MB of textures)
    
     * SKL GT3e (64MB eLLC) / Xorg / Unity:
       +4-8% GpuTest Triangle fullscreen (FullHD)
       -5-10% GpuTest Triangle windowed (1/2 screen)
    
     * SKL GT2 (no eLLC) / Xorg / Unity:
       * Some of the higher FPS SynMark pixel and vertex shader tests
         are few percent higher, more than daily variance
       => Do you see any reason why this machine would be impacted
          although it doesn't eLLC?"
    
    Caveats:
    - Still haven't tested with a prime setup
    - Still not entirely sure this a good idea, but I've been
      using it on my cfl anyway :)
    
    v2: Split the MOCS PTE change out
    
    Cc: Eero Tamminen <eero.t.tamminen@intel.com>
    Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
    Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    Link: https://patchwork.freedesktop.org/patch/msgid/20201007120329.17076-3-ville.syrjala@linux.intel.com
    Link: https://patchwork.freedesktop.org/patch/msgid/20201015122138.30161-3-chris@chris-wilson.co.uk
    c0888e9e
i915_drv.h 58 KB