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authorMatthew Auld2021-07-13 14:04:31 +0100
committerRodrigo Vivi2021-07-14 08:46:18 -0400
commit0abb33bfca0fb74df76aac03e90ce685016ef7be (patch)
tree47a4d026968fdc8ac2a740ff7665f789000ca302 /drivers/gpu
parent2feeb52859fc1ab94cd35b61ada3a6ac4ff24243 (diff)
drm/i915/gtt: drop the page table optimisation
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 <matthew.auld@intel.com> Cc: Jon Bloomfield <jon.bloomfield@intel.com> Cc: Chris Wilson <chris.p.wilson@intel.com> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: <stable@vger.kernel.org> # v4.15+ Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20210713130431.2392740-1-matthew.auld@intel.com (cherry picked from commit 8f88ca76b3942d82e2c1cea8735ec368d89ecc15) Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/i915/gt/gen8_ppgtt.c5
1 files changed, 1 insertions, 4 deletions
diff --git a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
index 21c8b7350b7a..da4f5eb43ac2 100644
--- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c
@@ -303,10 +303,7 @@ 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])) {