On Fri, 2017-09-29 at 17:10 +0100, Matthew Auld wrote:
> We can't mix 64K and 4K pte's in the same page-table, so for now we
> align 64K objects to 2M to avoid any potential mixing. This is
> potentially wasteful but in reality shouldn't be too bad since this only
> applies to the virtual address space of a 48b PPGTT.
>
> v2: don't separate logically connected ops
>
> Suggested-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
<SNIP>
> +++ b/drivers/gpu/drm/i915/i915_vma.c
> @@ -501,9 +501,18 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
> if (upper_32_bits(end) &&
> vma->page_sizes.sg > I915_GTT_PAGE_SIZE) {
Here. See below.
> u64 page_alignment =
> - rounddown_pow_of_two(vma->page_sizes.sg);
> + rounddown_pow_of_two(vma->page_sizes.sg |
> + I915_GTT_PAGE_SIZE_2M);
>
> alignment = max(alignment, page_alignment);
> +
> + /*
> + * We can't mix 64K and 4K PTEs in the same page-table (2M
> + * block), and so to avoid the ugliness and complexity of
> + * coloring we opt for just aligning 64K objects to 2M.
> + */
This is about size, the alignment is happening above, I'd lift the
comment there.
> + if (vma->page_sizes.sg & I915_GTT_PAGE_SIZE_64K)
> + size = round_up(size, I915_GTT_PAGE_SIZE_2M);
> }
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Regards, Joonas
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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