[v3,4/4] drm/i915: Use partial view in mmap fault handler
diff mbox

Message ID 1430912169.9311.9.camel@jlahtine-mobl1
State New
Headers show

Commit Message

Joonas Lahtinen May 6, 2015, 11:36 a.m. UTC
Use partial view for huge BOs (bigger than half the mappable aperture)
in fault handler so that they can be accessed withough trying to make
room for them by evicting other objects.

v2:
- Only use partial views in the case where early rejection was
  previously done.
- Account variable type changes from previous reroll.
v3:
- Add a comment about overwriting existing page entries.
  (Tvrtko Ursulin)
- Whitespace fixes.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c | 73 ++++++++++++++++++++++++++++-------------
 1 file changed, 51 insertions(+), 22 deletions(-)

Comments

Tvrtko Ursulin May 6, 2015, 12:33 p.m. UTC | #1
On 05/06/2015 12:36 PM, Joonas Lahtinen wrote:
>
> Use partial view for huge BOs (bigger than half the mappable aperture)
> in fault handler so that they can be accessed withough trying to make
> room for them by evicting other objects.
>
> v2:
> - Only use partial views in the case where early rejection was
>    previously done.
> - Account variable type changes from previous reroll.
> v3:
> - Add a comment about overwriting existing page entries.
>    (Tvrtko Ursulin)
> - Whitespace fixes.

Again I wish two vm_insert_pfn loops could be unified by making partial 
view a special case of normal, but as this is another area where 
imminent change has been hinted, and it doesn't matter hugely anyway:

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko
Shuang He May 7, 2015, 11:27 a.m. UTC | #2
Tested-By: Intel Graphics QA PRTS (Patch Regression Test System Contact: shuang.he@intel.com)
Task id: 6329
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                                  276/276              276/276
ILK                                  302/302              302/302
SNB                                  316/316              316/316
IVB                                  342/342              342/342
BYT                                  286/286              286/286
BDW                                  321/321              321/321
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
Note: You need to pay more attention to line start with '*'

Patch
diff mbox

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7e8eafe..488ae13 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1635,6 +1635,7 @@  int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 	struct drm_i915_gem_object *obj = to_intel_bo(vma->vm_private_data);
 	struct drm_device *dev = obj->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct i915_ggtt_view view = i915_ggtt_view_normal;
 	pgoff_t page_offset;
 	unsigned long pfn;
 	int ret = 0;
@@ -1667,8 +1668,21 @@  int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 		goto unlock;
 	}
 
-	/* Now bind it into the GTT if needed */
-	ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_MAPPABLE);
+	/* Use a partial view if the object is bigger than the aperture. */
+	if (obj->base.size >= dev_priv->gtt.mappable_end) {
+		static const unsigned int chunk_size = 256; // 1 MiB
+		memset(&view, 0, sizeof(view));
+		view.type = I915_GGTT_VIEW_PARTIAL;
+		view.params.partial.offset = rounddown(page_offset, chunk_size);
+		view.params.partial.size =
+			min_t(unsigned int,
+			      chunk_size,
+			      (vma->vm_end - vma->vm_start)/PAGE_SIZE -
+			      view.params.partial.offset);
+	}
+
+	/* Now pin it into the GTT if needed */
+	ret = i915_gem_object_ggtt_pin(obj, &view, 0, PIN_MAPPABLE);
 	if (ret)
 		goto unlock;
 
@@ -1681,30 +1695,50 @@  int i915_gem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 		goto unpin;
 
 	/* Finally, remap it using the new GTT offset */
-	pfn = dev_priv->gtt.mappable_base + i915_gem_obj_ggtt_offset(obj);
+	pfn = dev_priv->gtt.mappable_base +
+		i915_gem_obj_ggtt_offset_view(obj, &view);
 	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;
+	if (unlikely(view.type == I915_GGTT_VIEW_PARTIAL)) {
+		/* Overriding existing pages in partial view does not cause
+		 * us any trouble as TLBs are still valid because the fault
+		 * is due to userspace losing part of the mapping or never
+		 * having accessed it before (at this partials' range).
+		 */
+		unsigned long base = vma->vm_start +
+				     (view.params.partial.offset << PAGE_SHIFT);
+		unsigned int i;
 
-		for (i = 0; i < size >> PAGE_SHIFT; i++) {
-			ret = vm_insert_pfn(vma,
-					    (unsigned long)vma->vm_start + i * PAGE_SIZE,
-					    pfn + i);
+		for (i = 0; i < view.params.partial.size; i++) {
+			ret = vm_insert_pfn(vma, base + 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);
+	} else {
+		if (!obj->fault_mappable) {
+			unsigned long size = min_t(unsigned long,
+						   vma->vm_end - vma->vm_start,
+						   obj->base.size);
+			int i;
+
+			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;
+		} else
+			ret = vm_insert_pfn(vma,
+					    (unsigned long)vmf->virtual_address,
+					    pfn + page_offset);
+	}
 unpin:
-	i915_gem_object_ggtt_unpin(obj);
+	i915_gem_object_ggtt_unpin_view(obj, &view);
 unlock:
 	mutex_unlock(&dev->struct_mutex);
 out:
@@ -1897,11 +1931,6 @@  i915_gem_mmap_gtt(struct drm_file *file,
 		goto unlock;
 	}
 
-	if (obj->base.size > dev_priv->gtt.mappable_end) {
-		ret = -E2BIG;
-		goto out;
-	}
-
 	if (obj->madv != I915_MADV_WILLNEED) {
 		DRM_DEBUG("Attempting to mmap a purgeable buffer\n");
 		ret = -EFAULT;