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: 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>
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@ -4036,42 +4036,47 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
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lockdep_assert_held(&obj->base.dev->struct_mutex);
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if (!view && flags & PIN_MAPPABLE) {
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/* If the required space is larger than the available
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* aperture, we will not able to find a slot for the
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* object and unbinding the object now will be in
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* vain. Worse, doing so may cause us to ping-pong
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* the object in and out of the Global GTT and
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* waste a lot of cycles under the mutex.
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*/
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if (obj->base.size > dev_priv->ggtt.mappable_end)
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return ERR_PTR(-E2BIG);
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/* If NONBLOCK is set the caller is optimistically
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* trying to cache the full object within the mappable
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* aperture, and *must* have a fallback in place for
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* situations where we cannot bind the object. We
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* can be a little more lax here and use the fallback
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* more often to avoid costly migrations of ourselves
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* and other objects within the aperture.
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*
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* Half-the-aperture is used as a simple heuristic.
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* More interesting would to do search for a free
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* block prior to making the commitment to unbind.
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* That caters for the self-harm case, and with a
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* little more heuristics (e.g. NOFAULT, NOEVICT)
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* we could try to minimise harm to others.
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*/
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if (flags & PIN_NONBLOCK &&
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obj->base.size > dev_priv->ggtt.mappable_end / 2)
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return ERR_PTR(-ENOSPC);
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}
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vma = i915_vma_instance(obj, vm, view);
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if (unlikely(IS_ERR(vma)))
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return vma;
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if (i915_vma_misplaced(vma, size, alignment, flags)) {
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if (flags & PIN_NONBLOCK &&
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(i915_vma_is_pinned(vma) || i915_vma_is_active(vma)))
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return ERR_PTR(-ENOSPC);
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if (flags & PIN_NONBLOCK) {
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if (i915_vma_is_pinned(vma) || i915_vma_is_active(vma))
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return ERR_PTR(-ENOSPC);
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if (flags & PIN_MAPPABLE) {
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/* If the required space is larger than the available
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* aperture, we will not able to find a slot for the
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* object and unbinding the object now will be in
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* vain. Worse, doing so may cause us to ping-pong
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* the object in and out of the Global GTT and
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* waste a lot of cycles under the mutex.
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*/
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if (vma->fence_size > dev_priv->ggtt.mappable_end)
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return ERR_PTR(-E2BIG);
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/* If NONBLOCK is set the caller is optimistically
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* trying to cache the full object within the mappable
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* aperture, and *must* have a fallback in place for
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* situations where we cannot bind the object. We
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* can be a little more lax here and use the fallback
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* more often to avoid costly migrations of ourselves
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* and other objects within the aperture.
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*
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* Half-the-aperture is used as a simple heuristic.
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* More interesting would to do search for a free
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* block prior to making the commitment to unbind.
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* That caters for the self-harm case, and with a
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* little more heuristics (e.g. NOFAULT, NOEVICT)
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* we could try to minimise harm to others.
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*/
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if (flags & PIN_NONBLOCK &&
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if (flags & PIN_MAPPABLE &&
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vma->fence_size > dev_priv->ggtt.mappable_end / 2)
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return ERR_PTR(-ENOSPC);
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}
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