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Subject[PATCH v3 5/7] drm/vmwgfx: Use an RBtree instead of linked list for MOB resources
Date
From: Thomas Hellstrom <thellstrom@vmware.com>

With emulated coherent memory we need to be able to quickly look up
a resource from the MOB offset. Instead of traversing a linked list with
O(n) worst case, use an RBtree with O(log n) worst case complexity.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>
---
drivers/gpu/drm/vmwgfx/vmwgfx_bo.c | 5 ++--
drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 10 +++----
drivers/gpu/drm/vmwgfx/vmwgfx_resource.c | 33 +++++++++++++++++-------
3 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
index 869aeaec2f86..18e4b329e563 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
@@ -463,6 +463,7 @@ void vmw_bo_bo_free(struct ttm_buffer_object *bo)
struct vmw_buffer_object *vmw_bo = vmw_buffer_object(bo);

WARN_ON(vmw_bo->dirty);
+ WARN_ON(!RB_EMPTY_ROOT(&vmw_bo->res_tree));
vmw_bo_unmap(vmw_bo);
kfree(vmw_bo);
}
@@ -479,6 +480,7 @@ static void vmw_user_bo_destroy(struct ttm_buffer_object *bo)
struct vmw_buffer_object *vbo = &vmw_user_bo->vbo;

WARN_ON(vbo->dirty);
+ WARN_ON(!RB_EMPTY_ROOT(&vbo->res_tree));
vmw_bo_unmap(vbo);
ttm_prime_object_kfree(vmw_user_bo, prime);
}
@@ -514,8 +516,7 @@ int vmw_bo_init(struct vmw_private *dev_priv,
memset(vmw_bo, 0, sizeof(*vmw_bo));
BUILD_BUG_ON(TTM_MAX_BO_PRIORITY <= 3);
vmw_bo->base.priority = 3;
-
- INIT_LIST_HEAD(&vmw_bo->res_list);
+ vmw_bo->res_tree = RB_ROOT;

ret = ttm_bo_init(bdev, &vmw_bo->base, size,
ttm_bo_type_device, placement,
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 7944dbbbdd72..53f8522ae032 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -100,7 +100,7 @@ struct vmw_fpriv {
/**
* struct vmw_buffer_object - TTM buffer object with vmwgfx additions
* @base: The TTM buffer object
- * @res_list: List of resources using this buffer object as a backing MOB
+ * @res_tree: RB tree of resources using this buffer object as a backing MOB
* @pin_count: pin depth
* @dx_query_ctx: DX context if this buffer object is used as a DX query MOB
* @map: Kmap object for semi-persistent mappings
@@ -109,7 +109,7 @@ struct vmw_fpriv {
*/
struct vmw_buffer_object {
struct ttm_buffer_object base;
- struct list_head res_list;
+ struct rb_root res_tree;
s32 pin_count;
/* Not ref-counted. Protected by binding_mutex */
struct vmw_resource *dx_query_ctx;
@@ -157,8 +157,8 @@ struct vmw_res_func;
* pin-count greater than zero. It is not on the resource LRU lists and its
* backup buffer is pinned. Hence it can't be evicted.
* @func: Method vtable for this resource. Immutable.
+ * @mob_node; Node for the MOB backup rbtree. Protected by @backup reserved.
* @lru_head: List head for the LRU list. Protected by @dev_priv::resource_lock.
- * @mob_head: List head for the MOB backup list. Protected by @backup reserved.
* @binding_head: List head for the context binding list. Protected by
* the @dev_priv::binding_mutex
* @res_free: The resource destructor.
@@ -179,8 +179,8 @@ struct vmw_resource {
unsigned long backup_offset;
unsigned long pin_count;
const struct vmw_res_func *func;
+ struct rb_node mob_node;
struct list_head lru_head;
- struct list_head mob_head;
struct list_head binding_head;
struct vmw_resource_dirty *dirty;
void (*res_free) (struct vmw_resource *res);
@@ -733,7 +733,7 @@ void vmw_resource_dirty_update(struct vmw_resource *res, pgoff_t start,
*/
static inline bool vmw_resource_mob_attached(const struct vmw_resource *res)
{
- return !list_empty(&res->mob_head);
+ return !RB_EMPTY_NODE(&res->mob_node);
}

/**
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index e4c97a4cf2ff..328ad46076ff 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -40,11 +40,24 @@
void vmw_resource_mob_attach(struct vmw_resource *res)
{
struct vmw_buffer_object *backup = res->backup;
+ struct rb_node **new = &backup->res_tree.rb_node, *parent = NULL;

dma_resv_assert_held(res->backup->base.base.resv);
res->used_prio = (res->res_dirty) ? res->func->dirty_prio :
res->func->prio;
- list_add_tail(&res->mob_head, &backup->res_list);
+
+ while (*new) {
+ struct vmw_resource *this =
+ container_of(*new, struct vmw_resource, mob_node);
+
+ parent = *new;
+ new = (res->backup_offset < this->backup_offset) ?
+ &((*new)->rb_left) : &((*new)->rb_right);
+ }
+
+ rb_link_node(&res->mob_node, parent, new);
+ rb_insert_color(&res->mob_node, &backup->res_tree);
+
vmw_bo_prio_add(backup, res->used_prio);
}

@@ -58,7 +71,8 @@ void vmw_resource_mob_detach(struct vmw_resource *res)

dma_resv_assert_held(backup->base.base.resv);
if (vmw_resource_mob_attached(res)) {
- list_del_init(&res->mob_head);
+ rb_erase(&res->mob_node, &backup->res_tree);
+ RB_CLEAR_NODE(&res->mob_node);
vmw_bo_prio_del(backup, res->used_prio);
}
}
@@ -204,8 +218,8 @@ int vmw_resource_init(struct vmw_private *dev_priv, struct vmw_resource *res,
res->res_free = res_free;
res->dev_priv = dev_priv;
res->func = func;
+ RB_CLEAR_NODE(&res->mob_node);
INIT_LIST_HEAD(&res->lru_head);
- INIT_LIST_HEAD(&res->mob_head);
INIT_LIST_HEAD(&res->binding_head);
res->id = -1;
res->backup = NULL;
@@ -754,19 +768,20 @@ int vmw_resource_validate(struct vmw_resource *res, bool intr)
*/
void vmw_resource_unbind_list(struct vmw_buffer_object *vbo)
{
-
- struct vmw_resource *res, *next;
struct ttm_validate_buffer val_buf = {
.bo = &vbo->base,
.num_shared = 0
};

dma_resv_assert_held(vbo->base.base.resv);
- list_for_each_entry_safe(res, next, &vbo->res_list, mob_head) {
- if (!res->func->unbind)
- continue;
+ while (!RB_EMPTY_ROOT(&vbo->res_tree)) {
+ struct rb_node *node = vbo->res_tree.rb_node;
+ struct vmw_resource *res =
+ container_of(node, struct vmw_resource, mob_node);
+
+ if (!WARN_ON_ONCE(!res->func->unbind))
+ (void) res->func->unbind(res, res->res_dirty, &val_buf);

- (void) res->func->unbind(res, res->res_dirty, &val_buf);
res->backup_dirty = true;
res->res_dirty = false;
vmw_resource_mob_detach(res);
--
2.20.1
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