Currently, we try to report to the shrinker the precise number of
objects (pages) that are available to be reaped at this moment. This
requires searching all objects with allocated pages to see if they
fulfill the search criteria, and this count is performed quite
frequently. (The shrinker tries to free ~128 pages on each invocation,
before which we count all the objects; counting takes longer than
unbinding the objects!) If we take the pragmatic view that with
sufficient desire, all objects are eventually reapable (they become
inactive, or no longer used as framebuffer etc), we can simply return
the count of pinned pages maintained during get_pages/put_pages rather
than walk the lists every time.
The downside is that we may (slightly) over-report the number of
objects/pages we could shrink and so penalize ourselves by shrinking
more than required. This is mitigated by keeping the order in which we
shrink objects such that we avoid penalizing active and frequently used
objects, and if memory is so tight that we need to free them we would
need to anyway.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 2 +-
drivers/gpu/drm/i915/i915_drv.h | 1 -
drivers/gpu/drm/i915/i915_gem.c | 27 ++++-------------------
drivers/gpu/drm/i915/i915_gem_shrinker.c | 28 +++++-------------------
4 files changed, 11 insertions(+), 47 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 13e7b9e4a6e6..8262695019c4 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -434,7 +434,7 @@ static int i915_gem_object_info(struct seq_file *m, void *data)
if (ret)
return ret;
- seq_printf(m, "%u objects, %llu bytes\n",
+ seq_printf(m, "%u active objects, %llu bytes\n",
dev_priv->mm.object_count,
dev_priv->mm.object_memory);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index c7c0cb9636ce..0e23aa49a1a4 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -986,7 +986,6 @@ struct i915_gem_mm {
uint32_t bit_6_swizzle_y;
/* accounting, useful for userland debugging */
- spinlock_t object_stat_lock;
u64 object_memory;
u32 object_count;
};
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7d57b49eb577..2ff21cc2c562 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -77,25 +77,6 @@ remove_mappable_node(struct drm_mm_node *node)
drm_mm_remove_node(node);
}
-/* some bookkeeping */
-static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
- u64 size)
-{
- spin_lock(&dev_priv->mm.object_stat_lock);
- dev_priv->mm.object_count++;
- dev_priv->mm.object_memory += size;
- spin_unlock(&dev_priv->mm.object_stat_lock);
-}
-
-static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
- u64 size)
-{
- spin_lock(&dev_priv->mm.object_stat_lock);
- dev_priv->mm.object_count--;
- dev_priv->mm.object_memory -= size;
- spin_unlock(&dev_priv->mm.object_stat_lock);
-}
-
static int
i915_gem_wait_for_error(struct i915_gpu_error *error)
{
@@ -2419,6 +2400,8 @@ __i915_gem_object_unset_pages(struct drm_i915_gem_object *obj)
spin_lock(&i915->mm.obj_lock);
list_del(&obj->mm.link);
+ i915->mm.object_count--;
+ i915->mm.object_memory -= obj->base.size;
spin_unlock(&i915->mm.obj_lock);
if (obj->mm.mapping) {
@@ -2705,6 +2688,8 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
GEM_BUG_ON(!HAS_PAGE_SIZES(i915, obj->mm.page_sizes.sg));
spin_lock(&i915->mm.obj_lock);
+ i915->mm.object_count++;
+ i915->mm.object_memory += obj->base.size;
list_add(&obj->mm.link, &i915->mm.unbound_list);
spin_unlock(&i915->mm.obj_lock);
}
@@ -4674,8 +4659,6 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
obj->mm.madv = I915_MADV_WILLNEED;
INIT_RADIX_TREE(&obj->mm.get_page.radix, GFP_KERNEL | __GFP_NOWARN);
mutex_init(&obj->mm.get_page.lock);
-
- i915_gem_info_add_obj(to_i915(obj->base.dev), obj->base.size);
}
static const struct drm_i915_gem_object_ops i915_gem_object_ops = {
@@ -4863,7 +4846,6 @@ static void __i915_gem_free_objects(struct drm_i915_private *i915,
reservation_object_fini(&obj->__builtin_resv);
drm_gem_object_release(&obj->base);
- i915_gem_info_remove_obj(i915, obj->base.size);
kfree(obj->bit_17);
i915_gem_object_free(obj);
@@ -5589,7 +5571,6 @@ i915_gem_load_init_fences(struct drm_i915_private *dev_priv)
static void i915_gem_init__mm(struct drm_i915_private *i915)
{
- spin_lock_init(&i915->mm.object_stat_lock);
spin_lock_init(&i915->mm.obj_lock);
spin_lock_init(&i915->mm.free_lock);
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index ea5a6e2d62d2..2bf08631d264 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -309,30 +309,14 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
struct drm_i915_private *i915 =
container_of(shrinker, struct drm_i915_private, mm.shrinker);
- struct drm_i915_gem_object *obj;
- unsigned long num_objects = 0;
- unsigned long count = 0;
+ unsigned long num_objects;
+ unsigned long count;
- spin_lock(&i915->mm.obj_lock);
- list_for_each_entry(obj, &i915->mm.unbound_list, mm.link)
- if (can_release_pages(obj)) {
- count += obj->base.size >> PAGE_SHIFT;
- num_objects++;
- }
+ count = READ_ONCE(i915->mm.object_memory) >> PAGE_SHIFT;
+ num_objects = READ_ONCE(i915->mm.object_count);
- list_for_each_entry(obj, &i915->mm.bound_list, mm.link)
- if (!i915_gem_object_is_active(obj) && can_release_pages(obj)) {
- count += obj->base.size >> PAGE_SHIFT;
- num_objects++;
- }
- list_for_each_entry(obj, &i915->mm.purge_list, mm.link)
- if (!i915_gem_object_is_active(obj) && can_release_pages(obj)) {
- count += obj->base.size >> PAGE_SHIFT;
- num_objects++;
- }
- spin_unlock(&i915->mm.obj_lock);
-
- /* Update our preferred vmscan batch size for the next pass.
+ /*
+ * Update our preferred vmscan batch size for the next pass.
* Our rough guess for an effective batch size is roughly 2
* available GEM objects worth of pages. That is we don't want
* the shrinker to fire, until it is worth the cost of freeing an
--
2.17.0
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