Re: [PATCH 5/5] drm/i915: Use remap_io_mapping() to prefault all PTE in a single pass

[Joonas Lahtinen <joonas.lahtinen@linux.intel.com>]

On ti, 2015-04-07 at 17:31 +0100, Chris Wilson wrote:
> On an Ivybridge i7-3720qm with 1600MHz DDR3, with 32 fences,
> Upload rate for 2 linear surfaces:  8134MiB/s -> 8154MiB/s
> Upload rate for 2 tiled surfaces:   8625MiB/s -> 8632MiB/s
> Upload rate for 4 linear surfaces:  8127MiB/s -> 8134MiB/s
> Upload rate for 4 tiled surfaces:   8602MiB/s -> 8629MiB/s
> Upload rate for 8 linear surfaces:  8124MiB/s -> 8137MiB/s
> Upload rate for 8 tiled surfaces:   8603MiB/s -> 8624MiB/s
> Upload rate for 16 linear surfaces: 8123MiB/s -> 8128MiB/s
> Upload rate for 16 tiled surfaces:  8606MiB/s -> 8618MiB/s
> Upload rate for 32 linear surfaces: 8121MiB/s -> 8128MiB/s
> Upload rate for 32 tiled surfaces:  8605MiB/s -> 8614MiB/s
> Upload rate for 64 linear surfaces: 8121MiB/s -> 8127MiB/s
> Upload rate for 64 tiled surfaces:  3017MiB/s -> 5202MiB/s
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Testcase: igt/gem_fence_upload/performance
> Testcase: igt/gem_mmap_gtt
> Reviewed-by: Brad Volkin <bradley.d.volkin@intel.com>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

> Cc: linux-mm@kvack.org
> ---
>  drivers/gpu/drm/i915/i915_gem.c | 23 ++++++-----------------
>  1 file changed, 6 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 7ab8e0039790..90d772f72276 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1667,25 +1667,14 @@ int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  	pfn = dev_priv->gtt.mappable_base + i915_gem_obj_ggtt_offset(obj);
>  	pfn >>= PAGE_SHIFT;
>  
> -	if (!obj->fault_mappable) {
> -		unsigned long size = min_t(unsigned long,
> -					   vma->vm_end - vma->vm_start,
> -					   obj->base.size);
> -		int i;
> +	ret = remap_io_mapping(vma,
> +			       vma->vm_start, pfn, vma->vm_end - vma->vm_start,
> +			       dev_priv->gtt.mappable);
> +	if (ret)
> +		goto unpin;
>  
> -		for (i = 0; i < 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;
>  
> -		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:


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