From 1786384f52175794d86cd8344bfbb463c30fc231 Mon Sep 17 00:00:00 2001 From: Matthew Auld Date: Tue, 13 Jul 2021 14:04:31 +0100 Subject: [PATCH] drm/i915/gtt: drop the page table optimisation commit 0abb33bfca0fb74df76aac03e90ce685016ef7be upstream. We skip filling out the pt with scratch entries if the va range covers the entire pt, since we later have to fill it with the PTEs for the object pages anyway. However this might leave open a small window where the PTEs don't point to anything valid for the HW to consume. When for example using 2M GTT pages this fill_px() showed up as being quite significant in perf measurements, and ends up being completely wasted since we ignore the pt and just use the pde directly. Anyway, currently we have our PTE construction split between alloc and insert, which is probably slightly iffy nowadays, since the alloc doesn't actually allocate anything anymore, instead it just sets up the page directories and points the PTEs at the scratch page. Later when we do the insert step we re-program the PTEs again. Better might be to squash the alloc and insert into a single step, then bringing back this optimisation(along with some others) should be possible. Fixes: 14826673247e ("drm/i915: Only initialize partially filled pagetables") Signed-off-by: Matthew Auld Cc: Jon Bloomfield Cc: Chris Wilson Cc: Daniel Vetter Cc: # v4.15+ Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20210713130431.2392740-1-matthew.auld@intel.com (cherry picked from commit 8f88ca76b3942d82e2c1cea8735ec368d89ecc15) Signed-off-by: Rodrigo Vivi Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c index 74bf6fc8461fe..674ef8805c704 100644 --- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c +++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c @@ -304,10 +304,7 @@ static void __gen8_ppgtt_alloc(struct i915_address_space * const vm, __i915_gem_object_pin_pages(pt->base); i915_gem_object_make_unshrinkable(pt->base); - if (lvl || - gen8_pt_count(*start, end) < I915_PDES || - intel_vgpu_active(vm->i915)) - fill_px(pt, vm->scratch[lvl]->encode); + fill_px(pt, vm->scratch[lvl]->encode); spin_lock(&pd->lock); if (likely(!pd->entry[idx])) {