Commit 99a7f4da authored by Chris Wilson's avatar Chris Wilson Committed by Joonas Lahtinen
Browse files

drm/i915: Keep the most recently used active-fence upon discard 



Whenever an i915_active idles, we prune its tree of old fence slots to
prevent a gradual leak should it be used to track many, many timelines.
The downside is that we then have to frequently reallocate the rbtree.
A compromise is that we keep the most recently used fence slot, and
reuse that for the next active reference as that is the most likely
timeline to be reused.

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarThomas Hellström <thomas.hellstrom@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200731085015.32368-4-chris@chris-wilson.co.uk


Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
parent 5d934137

drivers/gpu/drm/i915/i915_active.c

+20 −7
Original line number Diff line number Diff line
@@ -130,8 +130,8 @@ static inline void debug_active_assert(struct i915_active *ref) { } 
static void

__active_retire(struct i915_active *ref)

{

	struct rb_root root = RB_ROOT;

	struct active_node *it, *n;

	struct rb_root root;

	unsigned long flags;



	GEM_BUG_ON(i915_active_is_idle(ref));
@@ -143,9 +143,21 @@ __active_retire(struct i915_active *ref) 
	GEM_BUG_ON(rcu_access_pointer(ref->excl.fence));

	debug_active_deactivate(ref);



	/* Even if we have not used the cache, we may still have a barrier */

	if (!ref->cache)

		ref->cache = fetch_node(ref->tree.rb_node);



	/* Keep the MRU cached node for reuse */

	if (ref->cache) {

		/* Discard all other nodes in the tree */

		rb_erase(&ref->cache->node, &ref->tree);

		root = ref->tree;

	ref->tree = RB_ROOT;

	ref->cache = NULL;



		/* Rebuild the tree with only the cached node */

		rb_link_node(&ref->cache->node, NULL, &ref->tree.rb_node);

		rb_insert_color(&ref->cache->node, &ref->tree);

		GEM_BUG_ON(ref->tree.rb_node != &ref->cache->node);

	}



	spin_unlock_irqrestore(&ref->tree_lock, flags);
@@ -156,6 +168,7 @@ __active_retire(struct i915_active *ref) 
	/* ... except if you wait on it, you must manage your own references! */

	wake_up_var(ref);



	/* Finally free the discarded timeline tree  */

	rbtree_postorder_for_each_entry_safe(it, n, &root, node) {

		GEM_BUG_ON(i915_active_fence_isset(&it->base));

		kmem_cache_free(global.slab_cache, it);
@@ -745,16 +758,16 @@ int i915_sw_fence_await_active(struct i915_sw_fence *fence, 
	return await_active(ref, flags, sw_await_fence, fence, fence);

}



#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)

void i915_active_fini(struct i915_active *ref)

{

	debug_active_fini(ref);

	GEM_BUG_ON(atomic_read(&ref->count));

	GEM_BUG_ON(work_pending(&ref->work));

	GEM_BUG_ON(!RB_EMPTY_ROOT(&ref->tree));

	mutex_destroy(&ref->mutex);



	if (ref->cache)

		kmem_cache_free(global.slab_cache, ref->cache);

}

#endif



static inline bool is_idle_barrier(struct active_node *node, u64 idx)

{

drivers/gpu/drm/i915/i915_active.h

+0 −4
Original line number Diff line number Diff line
@@ -217,11 +217,7 @@ i915_active_is_idle(const struct i915_active *ref) 
	return !atomic_read(&ref->count);

}



#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)

void i915_active_fini(struct i915_active *ref);

#else

static inline void i915_active_fini(struct i915_active *ref) { }

#endif



int i915_active_acquire_preallocate_barrier(struct i915_active *ref,

					    struct intel_engine_cs *engine);