drm/i915: Enable eLLC caching of display buffers for SKL+
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:Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by:
Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by:
Chris 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
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