Commit 43ae70d9 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Early rejection of mappable GGTT pin attempts for large bo 



Currently, we reject attempting to pin a large bo into the mappable
aperture, but only after trying to create the vma. Under debug kernels,
repeatedly creating and freeing that vma for an oversized bo consumes
one-third of the runtime for pwrite/pread tests as it is spent on
kmalloc/kfree tracking. If we move the rejection to before creating that
vma, we lose some accuracy of checking against the fence_size as opposed
to object size, though the fence can never be smaller than the object.
Note that the vma creation itself will reject an attempt to create a vma
larger than the GTT so we can remove one redundant test.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171009084401.29090-7-chris@chris-wilson.co.uk


Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
parent a3259ca9

drivers/gpu/drm/i915/i915_gem.c

+35 −30
Original line number Diff line number Diff line
@@ -4036,16 +4036,7 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj, 


	lockdep_assert_held(&obj->base.dev->struct_mutex);



	vma = i915_vma_instance(obj, vm, view);

	if (unlikely(IS_ERR(vma)))

		return vma;



	if (i915_vma_misplaced(vma, size, alignment, flags)) {

		if (flags & PIN_NONBLOCK &&

		    (i915_vma_is_pinned(vma) || i915_vma_is_active(vma)))

			return ERR_PTR(-ENOSPC);



		if (flags & PIN_MAPPABLE) {

	if (!view && flags & PIN_MAPPABLE) {

		/* If the required space is larger than the available

		 * aperture, we will not able to find a slot for the

		 * object and unbinding the object now will be in
@@ -4053,7 +4044,7 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj, 
		 * the object in and out of the Global GTT and

		 * waste a lot of cycles under the mutex.

		 */

			if (vma->fence_size > dev_priv->ggtt.mappable_end)

		if (obj->base.size > dev_priv->ggtt.mappable_end)

			return ERR_PTR(-E2BIG);



		/* If NONBLOCK is set the caller is optimistically
@@ -4072,6 +4063,20 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj, 
		 * we could try to minimise harm to others.

		 */

		if (flags & PIN_NONBLOCK &&

		    obj->base.size > dev_priv->ggtt.mappable_end / 2)

			return ERR_PTR(-ENOSPC);

	}



	vma = i915_vma_instance(obj, vm, view);

	if (unlikely(IS_ERR(vma)))

		return vma;



	if (i915_vma_misplaced(vma, size, alignment, flags)) {

		if (flags & PIN_NONBLOCK) {

			if (i915_vma_is_pinned(vma) || i915_vma_is_active(vma))

				return ERR_PTR(-ENOSPC);



			if (flags & PIN_MAPPABLE &&

			    vma->fence_size > dev_priv->ggtt.mappable_end / 2)

				return ERR_PTR(-ENOSPC);

		}

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