On Tue, Jun 10, 2014 at 04:14:40AM -0700, Chris Wilson wrote:
> Inserting additional PTEs has no side-effect for us as the pfn are fixed
> for the entire time the object is resident in the global GTT. The
> downside is that we pay the entire cost of faulting the object upon the
> first hit, for which we in return receive the benefit of removing the
> per-page faulting overhead.
>
> On an Ivybridge i7-3720qm with 1600MHz DDR3, with 32 fences,
> Upload rate for 2 linear surfaces: 8127MiB/s -> 8134MiB/s
> Upload rate for 2 tiled surfaces: 8607MiB/s -> 8625MiB/s
> Upload rate for 4 linear surfaces: 8127MiB/s -> 8127MiB/s
> Upload rate for 4 tiled surfaces: 8611MiB/s -> 8602MiB/s
> Upload rate for 8 linear surfaces: 8114MiB/s -> 8124MiB/s
> Upload rate for 8 tiled surfaces: 8601MiB/s -> 8603MiB/s
> Upload rate for 16 linear surfaces: 8110MiB/s -> 8123MiB/s
> Upload rate for 16 tiled surfaces: 8595MiB/s -> 8606MiB/s
> Upload rate for 32 linear surfaces: 8104MiB/s -> 8121MiB/s
> Upload rate for 32 tiled surfaces: 8589MiB/s -> 8605MiB/s
> Upload rate for 64 linear surfaces: 8107MiB/s -> 8121MiB/s
> Upload rate for 64 tiled surfaces: 2013MiB/s -> 3017MiB/s
>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: "Goel, Akash" <akash.goel@xxxxxxxxx>
For reproducibility it would be nice to have the testcase info, assuming
it's something from i-g-t. Other than that, I think this change looks good.
Reviewed-by: Brad Volkin <bradley.d.volkin@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_gem.c | 22 +++++++++++++++++-----
> 1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 3aaf7e01235e..e1f68f06c2ef 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1704,14 +1704,26 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
> if (ret)
> goto unpin;
>
> - obj->fault_mappable = true;
> -
> + /* Finally, remap it using the new GTT offset */
> pfn = dev_priv->gtt.mappable_base + i915_gem_obj_ggtt_offset(obj);
> pfn >>= PAGE_SHIFT;
> - pfn += page_offset;
>
> - /* Finally, remap it using the new GTT offset */
> - ret = vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
> + if (!obj->fault_mappable) {
> + int i;
> +
> + for (i = 0; i < obj->base.size >> PAGE_SHIFT; i++) {
> + ret = vm_insert_pfn(vma,
> + (unsigned long)vma->vm_start + i * PAGE_SIZE,
> + pfn + i);
> + if (ret)
> + break;
> + }
> +
> + obj->fault_mappable = true;
> + } else
> + ret = vm_insert_pfn(vma,
> + (unsigned long)vmf->virtual_address,
> + pfn + page_offset);
> unpin:
> i915_gem_object_ggtt_unpin(obj);
> unlock:
> --
> 2.0.0
>
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