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

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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: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171009084401.29090-7-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Chris Wilson 2017-10-09 09:44:01 +01:00
parent a3259ca9f8
commit 43ae70d97c
1 changed files with 35 additions and 30 deletions
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65
drivers/gpu/drm/i915/i915_gem.c
View file

@ -4036,42 +4036,47 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
lockdep_assert_held(&obj->base.dev->struct_mutex);
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
* vain. Worse, doing so may cause us to ping-pong
* the object in and out of the Global GTT and
* waste a lot of cycles under the mutex.
*/
if (obj->base.size > dev_priv->ggtt.mappable_end)
return ERR_PTR(-E2BIG);
/* If NONBLOCK is set the caller is optimistically
* trying to cache the full object within the mappable
* aperture, and *must* have a fallback in place for
* situations where we cannot bind the object. We
* can be a little more lax here and use the fallback
* more often to avoid costly migrations of ourselves
* and other objects within the aperture.
*
* Half-the-aperture is used as a simple heuristic.
* More interesting would to do search for a free
* block prior to making the commitment to unbind.
* That caters for the self-harm case, and with a
* little more heuristics (e.g. NOFAULT, NOEVICT)
* 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 &&
(i915_vma_is_pinned(vma) || i915_vma_is_active(vma)))
return ERR_PTR(-ENOSPC);
if (flags & PIN_NONBLOCK) {
if (i915_vma_is_pinned(vma) || i915_vma_is_active(vma))
return ERR_PTR(-ENOSPC);
if (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
* vain. Worse, doing so may cause us to ping-pong
* 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)
return ERR_PTR(-E2BIG);
/* If NONBLOCK is set the caller is optimistically
* trying to cache the full object within the mappable
* aperture, and *must* have a fallback in place for
* situations where we cannot bind the object. We
* can be a little more lax here and use the fallback
* more often to avoid costly migrations of ourselves
* and other objects within the aperture.
*
* Half-the-aperture is used as a simple heuristic.
* More interesting would to do search for a free
* block prior to making the commitment to unbind.
* That caters for the self-harm case, and with a
* little more heuristics (e.g. NOFAULT, NOEVICT)
* we could try to minimise harm to others.
*/
if (flags & PIN_NONBLOCK &&
if (flags & PIN_MAPPABLE &&
vma->fence_size > dev_priv->ggtt.mappable_end / 2)
return ERR_PTR(-ENOSPC);
}