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

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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: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200731085015.32368-4-chris@chris-wilson.co.uk
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Chris Wilson 2020-07-31 09:50:12 +01:00 committed by Joonas Lahtinen
parent 5d9341370f
commit 99a7f4dae7
2 changed files with 20 additions and 11 deletions
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27
drivers/gpu/drm/i915/i915_active.c
View File

@ -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);
root = ref->tree;
ref->tree = RB_ROOT;
ref->cache = NULL;
/* 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;
/* 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)
{

4
drivers/gpu/drm/i915/i915_active.h
View File

@ -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);