drm/i915: Register a shrinker to free inactive lists under memory pressure
This should help GEM handle memory pressure sitatuions more gracefully.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 77cc6f5..2fff2e0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -53,6 +53,9 @@
struct drm_i915_gem_pwrite *args,
struct drm_file *file_priv);
+static LIST_HEAD(shrink_list);
+static DEFINE_SPINLOCK(shrink_list_lock);
+
int i915_gem_do_init(struct drm_device *dev, unsigned long start,
unsigned long end)
{
@@ -4265,6 +4268,10 @@
i915_gem_retire_work_handler);
dev_priv->mm.next_gem_seqno = 1;
+ spin_lock(&shrink_list_lock);
+ list_add(&dev_priv->mm.shrink_list, &shrink_list);
+ spin_unlock(&shrink_list_lock);
+
/* Old X drivers will take 0-2 for front, back, depth buffers */
dev_priv->fence_reg_start = 3;
@@ -4482,3 +4489,140 @@
list_del_init(i915_file_priv->mm.request_list.next);
mutex_unlock(&dev->struct_mutex);
}
+
+/* Immediately discard the backing storage */
+static void
+i915_gem_object_truncate(struct drm_gem_object *obj)
+{
+ struct inode *inode;
+
+ inode = obj->filp->f_path.dentry->d_inode;
+
+ mutex_lock(&inode->i_mutex);
+ truncate_inode_pages(inode->i_mapping, 0);
+ mutex_unlock(&inode->i_mutex);
+}
+
+static inline int
+i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj_priv)
+{
+ return !obj_priv->dirty;
+}
+
+static int
+i915_gem_shrink(int nr_to_scan, gfp_t gfp_mask)
+{
+ drm_i915_private_t *dev_priv, *next_dev;
+ struct drm_i915_gem_object *obj_priv, *next_obj;
+ int cnt = 0;
+ int would_deadlock = 1;
+
+ /* "fast-path" to count number of available objects */
+ if (nr_to_scan == 0) {
+ spin_lock(&shrink_list_lock);
+ list_for_each_entry(dev_priv, &shrink_list, mm.shrink_list) {
+ struct drm_device *dev = dev_priv->dev;
+
+ if (mutex_trylock(&dev->struct_mutex)) {
+ list_for_each_entry(obj_priv,
+ &dev_priv->mm.inactive_list,
+ list)
+ cnt++;
+ mutex_unlock(&dev->struct_mutex);
+ }
+ }
+ spin_unlock(&shrink_list_lock);
+
+ return (cnt / 100) * sysctl_vfs_cache_pressure;
+ }
+
+ spin_lock(&shrink_list_lock);
+
+ /* first scan for clean buffers */
+ list_for_each_entry_safe(dev_priv, next_dev,
+ &shrink_list, mm.shrink_list) {
+ struct drm_device *dev = dev_priv->dev;
+
+ if (! mutex_trylock(&dev->struct_mutex))
+ continue;
+
+ spin_unlock(&shrink_list_lock);
+
+ i915_gem_retire_requests(dev);
+
+ list_for_each_entry_safe(obj_priv, next_obj,
+ &dev_priv->mm.inactive_list,
+ list) {
+ if (i915_gem_object_is_purgeable(obj_priv)) {
+ struct drm_gem_object *obj = obj_priv->obj;
+ i915_gem_object_unbind(obj);
+ i915_gem_object_truncate(obj);
+
+ if (--nr_to_scan <= 0)
+ break;
+ }
+ }
+
+ spin_lock(&shrink_list_lock);
+ mutex_unlock(&dev->struct_mutex);
+
+ if (nr_to_scan <= 0)
+ break;
+ }
+
+ /* second pass, evict/count anything still on the inactive list */
+ list_for_each_entry_safe(dev_priv, next_dev,
+ &shrink_list, mm.shrink_list) {
+ struct drm_device *dev = dev_priv->dev;
+
+ if (! mutex_trylock(&dev->struct_mutex))
+ continue;
+
+ spin_unlock(&shrink_list_lock);
+
+ list_for_each_entry_safe(obj_priv, next_obj,
+ &dev_priv->mm.inactive_list,
+ list) {
+ if (nr_to_scan > 0) {
+ struct drm_gem_object *obj = obj_priv->obj;
+ i915_gem_object_unbind(obj);
+ if (i915_gem_object_is_purgeable(obj_priv))
+ i915_gem_object_truncate(obj);
+
+ nr_to_scan--;
+ } else
+ cnt++;
+ }
+
+ spin_lock(&shrink_list_lock);
+ mutex_unlock(&dev->struct_mutex);
+
+ would_deadlock = 0;
+ }
+
+ spin_unlock(&shrink_list_lock);
+
+ if (would_deadlock)
+ return -1;
+ else if (cnt > 0)
+ return (cnt / 100) * sysctl_vfs_cache_pressure;
+ else
+ return 0;
+}
+
+static struct shrinker shrinker = {
+ .shrink = i915_gem_shrink,
+ .seeks = DEFAULT_SEEKS,
+};
+
+__init void
+i915_gem_shrinker_init(void)
+{
+ register_shrinker(&shrinker);
+}
+
+__exit void
+i915_gem_shrinker_exit(void)
+{
+ unregister_shrinker(&shrinker);
+}