drm/i915: Replace execbuf vma ht with an idr

This was the competing idea long ago, but it was only with the rewrite
of the idr as an radixtree and using the radixtree directly ourselves,
along with the realisation that we can store the vma directly in the
radixtree and only need a list for the reverse mapping, that made the
patch performant enough to displace using a hashtable. Though the vma ht
is fast and doesn't require any extra allocation (as we can embed the node
inside the vma), it does require a thread for resizing and serialization
and will have the occasional slow lookup. That is hairy enough to
investigate alternatives and favour them if equivalent in peak performance.
One advantage of allocating an indirection entry is that we can support a
single shared bo between many clients, something that was done on a
first-come first-serve basis for shared GGTT vma previously. To offset
the extra allocations, we create yet another kmem_cache for them.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170816085210.4199-5-chris@chris-wilson.co.uk

1 files changed, 31 insertions, 15 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5a3f3bb3f21d..b9e8e0d6e97b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3242,25 +3242,33 @@ out_rearm:
 
 void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
 {
+	struct drm_i915_private *i915 = to_i915(gem->dev);
 	struct drm_i915_gem_object *obj = to_intel_bo(gem);
 	struct drm_i915_file_private *fpriv = file->driver_priv;
-	struct i915_vma *vma, *vn;
+	struct i915_lut_handle *lut, *ln;
 
-	mutex_lock(&obj->base.dev->struct_mutex);
-	list_for_each_entry_safe(vma, vn, &obj->vma_list, obj_link)
-		if (vma->vm->file == fpriv)
+	mutex_lock(&i915->drm.struct_mutex);
+
+	list_for_each_entry_safe(lut, ln, &obj->lut_list, obj_link) {
+		struct i915_gem_context *ctx = lut->ctx;
+		struct i915_vma *vma;
+
+		if (ctx->file_priv != fpriv)
+			continue;
+
+		vma = radix_tree_delete(&ctx->handles_vma, lut->handle);
+
+		if (!i915_vma_is_ggtt(vma))
 			i915_vma_close(vma);
 
-	vma = obj->vma_hashed;
-	if (vma && vma->ctx->file_priv == fpriv)
-		i915_vma_unlink_ctx(vma);
+		list_del(&lut->obj_link);
+		list_del(&lut->ctx_link);
 
-	if (i915_gem_object_is_active(obj) &&
-	    !i915_gem_object_has_active_reference(obj)) {
-		i915_gem_object_set_active_reference(obj);
-		i915_gem_object_get(obj);
+		kmem_cache_free(i915->luts, lut);
+		__i915_gem_object_release_unless_active(obj);
 	}
-	mutex_unlock(&obj->base.dev->struct_mutex);
+
+	mutex_unlock(&i915->drm.struct_mutex);
 }
 
 static unsigned long to_wait_timeout(s64 timeout_ns)
@@ -4252,6 +4260,7 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
 	INIT_LIST_HEAD(&obj->global_link);
 	INIT_LIST_HEAD(&obj->userfault_link);
 	INIT_LIST_HEAD(&obj->vma_list);
+	INIT_LIST_HEAD(&obj->lut_list);
 	INIT_LIST_HEAD(&obj->batch_pool_link);
 
 	obj->ops = ops;
@@ -4495,8 +4504,8 @@ void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj)
 {
 	lockdep_assert_held(&obj->base.dev->struct_mutex);
 
-	GEM_BUG_ON(i915_gem_object_has_active_reference(obj));
-	if (i915_gem_object_is_active(obj))
+	if (!i915_gem_object_has_active_reference(obj) &&
+	    i915_gem_object_is_active(obj))
 		i915_gem_object_set_active_reference(obj);
 	else
 		i915_gem_object_put(obj);
@@ -4888,12 +4897,16 @@ i915_gem_load_init(struct drm_i915_private *dev_priv)
 	if (!dev_priv->vmas)
 		goto err_objects;
 
+	dev_priv->luts = KMEM_CACHE(i915_lut_handle, 0);
+	if (!dev_priv->luts)
+		goto err_vmas;
+
 	dev_priv->requests = KMEM_CACHE(drm_i915_gem_request,
 					SLAB_HWCACHE_ALIGN |
 					SLAB_RECLAIM_ACCOUNT |
 					SLAB_TYPESAFE_BY_RCU);
 	if (!dev_priv->requests)
-		goto err_vmas;
+		goto err_luts;
 
 	dev_priv->dependencies = KMEM_CACHE(i915_dependency,
 					    SLAB_HWCACHE_ALIGN |
@@ -4937,6 +4950,8 @@ err_dependencies:
 	kmem_cache_destroy(dev_priv->dependencies);
 err_requests:
 	kmem_cache_destroy(dev_priv->requests);
+err_luts:
+	kmem_cache_destroy(dev_priv->luts);
 err_vmas:
 	kmem_cache_destroy(dev_priv->vmas);
 err_objects:
@@ -4959,6 +4974,7 @@ void i915_gem_load_cleanup(struct drm_i915_private *dev_priv)
 	kmem_cache_destroy(dev_priv->priorities);
 	kmem_cache_destroy(dev_priv->dependencies);
 	kmem_cache_destroy(dev_priv->requests);
+	kmem_cache_destroy(dev_priv->luts);
 	kmem_cache_destroy(dev_priv->vmas);
 	kmem_cache_destroy(dev_priv->objects);