Break the allocation of the backing storage away from struct_mutex into
a per-object lock. This allows parallel page allocation, provided we can
do so outside of struct_mutex (i.e. set-domain-ioctl, pwrite, GTT
fault), i.e. before execbuf! The increased cost of the atomic counters
are hidden behind i915_vma_pin() for the typical case of execbuf, i.e.
as the object is typically bound between execbufs, the page_pin_count is
static. The cost will be felt around set-domain and pwrite, but offset
by the improvement from reduced struct_mutex contention.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 36 +++++--------
drivers/gpu/drm/i915/i915_gem.c | 93 +++++++++++++++++++++-----------
drivers/gpu/drm/i915/i915_gem_shrinker.c | 51 ++++++++++++------
drivers/gpu/drm/i915/i915_gem_tiling.c | 2 +
drivers/gpu/drm/i915/i915_gem_userptr.c | 10 ++--
5 files changed, 114 insertions(+), 78 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a8b75a1f6656..454bd563af9e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2274,7 +2274,8 @@ struct drm_i915_gem_object {
unsigned int pin_display;
struct {
- unsigned int pages_pin_count;
+ struct mutex lock; /* protects the pages and their use */
+ atomic_t pages_pin_count;
struct sg_table *pages;
void *mapping;
@@ -2387,13 +2388,6 @@ i915_gem_object_is_dead(const struct drm_i915_gem_object *obj)
return atomic_read(&obj->base.refcount.refcount) == 0;
}
-#if IS_ENABLED(CONFIG_LOCKDEP)
-#define lockdep_assert_held_unless(lock, cond) \
- GEM_BUG_ON(debug_locks && !lockdep_is_held(lock) && !(cond))
-#else
-#define lockdep_assert_held_unless(lock, cond)
-#endif
-
static inline bool
i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj)
{
@@ -3229,9 +3223,9 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj);
static inline int __must_check
i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
{
- lockdep_assert_held(&obj->base.dev->struct_mutex);
+ might_lock(&obj->mm.lock);
- if (obj->mm.pages_pin_count++)
+ if (atomic_inc_not_zero(&obj->mm.pages_pin_count))
return 0;
return __i915_gem_object_get_pages(obj);
@@ -3240,32 +3234,29 @@ i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
static inline void
__i915_gem_object_pin_pages(struct drm_i915_gem_object *obj)
{
- lockdep_assert_held_unless(&obj->base.dev->struct_mutex,
- i915_gem_object_is_dead(obj));
GEM_BUG_ON(!obj->mm.pages);
- obj->mm.pages_pin_count++;
+ atomic_inc(&obj->mm.pages_pin_count);
}
static inline bool
i915_gem_object_has_pinned_pages(struct drm_i915_gem_object *obj)
{
- return obj->mm.pages_pin_count;
+ return atomic_read(&obj->mm.pages_pin_count);
}
static inline void
__i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
{
- lockdep_assert_held_unless(&obj->base.dev->struct_mutex,
- i915_gem_object_is_dead(obj));
GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
GEM_BUG_ON(!obj->mm.pages);
- obj->mm.pages_pin_count--;
- GEM_BUG_ON(obj->mm.pages_pin_count < obj->bind_count);
+ atomic_dec(&obj->mm.pages_pin_count);
+ GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
}
-static inline void i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
+static inline void
+i915_gem_object_unpin_pages(struct drm_i915_gem_object *obj)
{
__i915_gem_object_unpin_pages(obj);
}
@@ -3288,8 +3279,8 @@ enum i915_map_type {
* the kernel address space. Based on the @type of mapping, the PTE will be
* set to either WriteBack or WriteCombine (via pgprot_t).
*
- * The caller must hold the struct_mutex, and is responsible for calling
- * i915_gem_object_unpin_map() when the mapping is no longer required.
+ * The caller is responsible for calling i915_gem_object_unpin_map() when the
+ * mapping is no longer required.
*
* Returns the pointer through which to access the mapped object, or an
* ERR_PTR() on error.
@@ -3305,12 +3296,9 @@ void *__must_check i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
* with your access, call i915_gem_object_unpin_map() to release the pin
* upon the mapping. Once the pin count reaches zero, that mapping may be
* removed.
- *
- * The caller must hold the struct_mutex.
*/
static inline void i915_gem_object_unpin_map(struct drm_i915_gem_object *obj)
{
- lockdep_assert_held(&obj->base.dev->struct_mutex);
i915_gem_object_unpin_pages(obj);
}
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 56060aeb12e3..c8e9548adfeb 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2269,6 +2269,9 @@ void __i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
{
struct address_space *mapping;
+ lockdep_assert_held(&obj->mm.lock);
+ GEM_BUG_ON(obj->mm.pages);
+
switch (obj->mm.madv) {
case I915_MADV_DONTNEED:
i915_gem_object_truncate(obj);
@@ -2325,12 +2328,17 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
{
struct sg_table *pages;
- lockdep_assert_held(&obj->base.dev->struct_mutex);
-
if (i915_gem_object_has_pinned_pages(obj))
return;
GEM_BUG_ON(obj->bind_count);
+ if (!READ_ONCE(obj->mm.pages))
+ return;
+
+ /* May be called by shrinker from within get_pages() (on another bo) */
+ mutex_lock_nested(&obj->mm.lock, SINGLE_DEPTH_NESTING);
+ if (unlikely(atomic_read(&obj->mm.pages_pin_count)))
+ goto unlock;
/* ->put_pages might need to allocate memory for the bit17 swizzle
* array, hence protect them from being reaped by removing them from gtt
@@ -2353,6 +2361,8 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
__i915_gem_object_reset_page_iter(obj);
obj->ops->put_pages(obj, pages);
+unlock:
+ mutex_unlock(&obj->mm.lock);
}
static unsigned int swiotlb_max_size(void)
@@ -2486,7 +2496,7 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
struct sg_table *pages)
{
- lockdep_assert_held(&obj->base.dev->struct_mutex);
+ lockdep_assert_held(&obj->mm.lock);
obj->mm.get_page.sg_pos = pages->sgl;
obj->mm.get_page.sg_idx = 0;
@@ -2512,9 +2522,9 @@ static int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
}
/* Ensure that the associated pages are gathered from the backing storage
- * and pinned into our object. i915_gem_object_get_pages() may be called
+ * and pinned into our object. i915_gem_object_pin_pages() may be called
* multiple times before they are released by a single call to
- * i915_gem_object_put_pages() - once the pages are no longer referenced
+ * i915_gem_object_unpin_pages() - once the pages are no longer referenced
* either as a result of memory pressure (reaping pages under the shrinker)
* or as the object is itself released.
*/
@@ -2522,15 +2532,23 @@ int __i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
int err;
- lockdep_assert_held(&obj->base.dev->struct_mutex);
+ err = mutex_lock_interruptible(&obj->mm.lock);
+ if (err)
+ return err;
- if (obj->mm.pages)
- return 0;
+ if (likely(obj->mm.pages)) {
+ __i915_gem_object_pin_pages(obj);
+ goto unlock;
+ }
+
+ GEM_BUG_ON(i915_gem_object_has_pinned_pages(obj));
err = ____i915_gem_object_get_pages(obj);
- if (err)
- __i915_gem_object_unpin_pages(obj);
+ if (!err)
+ atomic_set_release(&obj->mm.pages_pin_count, 1);
+unlock:
+ mutex_unlock(&obj->mm.lock);
return err;
}
@@ -2590,20 +2608,29 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
void *ptr;
int ret;
- lockdep_assert_held(&obj->base.dev->struct_mutex);
GEM_BUG_ON(!i915_gem_object_has_struct_page(obj));
- ret = i915_gem_object_pin_pages(obj);
+ ret = mutex_lock_interruptible(&obj->mm.lock);
if (ret)
return ERR_PTR(ret);
- pinned = obj->mm.pages_pin_count > 1;
+ pinned = true;
+ if (!atomic_inc_not_zero(&obj->mm.pages_pin_count)) {
+ ret = ____i915_gem_object_get_pages(obj);
+ if (ret)
+ goto err_unlock;
+
+ GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count));
+ atomic_set_release(&obj->mm.pages_pin_count, 1);
+ pinned = false;
+ }
+ GEM_BUG_ON(!obj->mm.pages);
ptr = ptr_unpack_bits(obj->mm.mapping, has_type);
if (ptr && has_type != type) {
if (pinned) {
ret = -EBUSY;
- goto err;
+ goto err_unpin;
}
if (is_vmalloc_addr(ptr))
@@ -2618,17 +2645,21 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
ptr = i915_gem_object_map(obj, type);
if (!ptr) {
ret = -ENOMEM;
- goto err;
+ goto err_unpin;
}
obj->mm.mapping = ptr_pack_bits(ptr, type);
}
+out_unlock:
+ mutex_unlock(&obj->mm.lock);
return ptr;
-err:
- i915_gem_object_unpin_pages(obj);
- return ERR_PTR(ret);
+err_unpin:
+ atomic_dec(&obj->mm.pages_pin_count);
+err_unlock:
+ ptr = ERR_PTR(ret);
+ goto out_unlock;
}
static void
@@ -4268,7 +4299,7 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
struct drm_i915_private *dev_priv = to_i915(dev);
struct drm_i915_gem_madvise *args = data;
struct drm_i915_gem_object *obj;
- int ret;
+ int err;
switch (args->madv) {
case I915_MADV_DONTNEED:
@@ -4278,15 +4309,13 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
return -EINVAL;
}
- ret = i915_mutex_lock_interruptible(dev);
- if (ret)
- return ret;
-
obj = i915_gem_object_lookup(file_priv, args->handle);
- if (!obj) {
- ret = -ENOENT;
- goto unlock;
- }
+ if (!obj)
+ return -ENOENT;
+
+ err = mutex_lock_interruptible(&obj->mm.lock);
+ if (err)
+ goto out;
if (obj->mm.pages &&
i915_gem_object_is_tiled(obj) &&
@@ -4305,11 +4334,11 @@ i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
i915_gem_object_truncate(obj);
args->retained = obj->mm.madv != __I915_MADV_PURGED;
+ mutex_unlock(&obj->mm.lock);
+out:
i915_gem_object_put(obj);
-unlock:
- mutex_unlock(&dev->struct_mutex);
- return ret;
+ return err;
}
void i915_gem_object_init(struct drm_i915_gem_object *obj,
@@ -4317,6 +4346,8 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
{
int i;
+ mutex_init(&obj->mm.lock);
+
INIT_LIST_HEAD(&obj->global_list);
INIT_LIST_HEAD(&obj->userfault_link);
for (i = 0; i < I915_NUM_ENGINES; i++)
@@ -4479,7 +4510,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
obj->ops->release(obj);
if (WARN_ON(i915_gem_object_has_pinned_pages(obj)))
- obj->mm.pages_pin_count = 0;
+ atomic_set(&obj->mm.pages_pin_count, 0);
if (discard_backing_storage(obj))
obj->mm.madv = I915_MADV_DONTNEED;
__i915_gem_object_put_pages(obj);
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index f95061faeae6..c8a4c40ec2c2 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -48,6 +48,20 @@ static bool mutex_is_locked_by(struct mutex *mutex, struct task_struct *task)
#endif
}
+static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
+{
+ if (!mutex_trylock(&dev->struct_mutex)) {
+ if (!mutex_is_locked_by(&dev->struct_mutex, current))
+ return false;
+
+ *unlock = false;
+ } else {
+ *unlock = true;
+ }
+
+ return true;
+}
+
static bool any_vma_pinned(struct drm_i915_gem_object *obj)
{
struct i915_vma *vma;
@@ -66,6 +80,9 @@ static bool swap_available(void)
static bool can_release_pages(struct drm_i915_gem_object *obj)
{
+ if (!obj->mm.pages)
+ return false;
+
/* Only shmemfs objects are backed by swap */
if (!obj->base.filp)
return false;
@@ -78,7 +95,7 @@ static bool can_release_pages(struct drm_i915_gem_object *obj)
* to the GPU, simply unbinding from the GPU is not going to succeed
* in releasing our pin count on the pages themselves.
*/
- if (obj->mm.pages_pin_count > obj->bind_count)
+ if (atomic_read(&obj->mm.pages_pin_count) > obj->bind_count)
return false;
if (any_vma_pinned(obj))
@@ -95,7 +112,7 @@ static bool unsafe_drop_pages(struct drm_i915_gem_object *obj)
{
if (i915_gem_object_unbind(obj) == 0)
__i915_gem_object_put_pages(obj);
- return !obj->mm.pages;
+ return !READ_ONCE(obj->mm.pages);
}
/**
@@ -135,6 +152,10 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
{ NULL, 0 },
}, *phase;
unsigned long count = 0;
+ bool unlock;
+
+ if (!i915_gem_shrinker_lock(&dev_priv->drm, &unlock))
+ return 0;
trace_i915_gem_shrink(dev_priv, target, flags);
i915_gem_retire_requests(dev_priv);
@@ -199,8 +220,14 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
i915_gem_object_get(obj);
- if (unsafe_drop_pages(obj))
- count += obj->base.size >> PAGE_SHIFT;
+ if (unsafe_drop_pages(obj)) {
+ mutex_lock(&obj->mm.lock);
+ if (!obj->mm.pages) {
+ __i915_gem_object_invalidate(obj);
+ count += obj->base.size >> PAGE_SHIFT;
+ }
+ mutex_unlock(&obj->mm.lock);
+ }
i915_gem_object_put(obj);
}
@@ -211,6 +238,9 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
intel_runtime_pm_put(dev_priv);
i915_gem_retire_requests(dev_priv);
+ if (unlock)
+ mutex_unlock(&dev_priv->drm.struct_mutex);
+
/* expedite the RCU grace period to free some request slabs */
synchronize_rcu_expedited();
@@ -244,19 +274,6 @@ unsigned long i915_gem_shrink_all(struct drm_i915_private *dev_priv)
return freed;
}
-static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
-{
- if (!mutex_trylock(&dev->struct_mutex)) {
- if (!mutex_is_locked_by(&dev->struct_mutex, current))
- return false;
-
- *unlock = false;
- } else
- *unlock = true;
-
- return true;
-}
-
static unsigned long
i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
{
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index 34d5ada49720..6608799ee1f9 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -259,6 +259,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
if (!err) {
struct i915_vma *vma;
+ mutex_lock(&obj->mm.lock);
if (obj->mm.pages &&
obj->mm.madv == I915_MADV_WILLNEED &&
dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
@@ -267,6 +268,7 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
if (!i915_gem_object_is_tiled(obj))
__i915_gem_object_pin_pages(obj);
}
+ mutex_unlock(&obj->mm.lock);
list_for_each_entry(vma, &obj->vma_list, obj_link) {
if (!vma->fence)
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index a421447f1d84..6c8c7b36f7fc 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -79,7 +79,7 @@ static void cancel_userptr(struct work_struct *work)
WARN_ONCE(obj->mm.pages,
"Failed to release pages: bind_count=%d, pages_pin_count=%d, pin_display=%d\n",
obj->bind_count,
- obj->mm.pages_pin_count,
+ atomic_read(&obj->mm.pages_pin_count),
obj->pin_display);
i915_gem_object_put(obj);
@@ -491,7 +491,6 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
{
struct get_pages_work *work = container_of(_work, typeof(*work), work);
struct drm_i915_gem_object *obj = work->obj;
- struct drm_device *dev = obj->base.dev;
const int npages = obj->base.size >> PAGE_SHIFT;
struct page **pvec;
int pinned, ret;
@@ -527,7 +526,7 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
}
}
- mutex_lock(&dev->struct_mutex);
+ mutex_lock(&obj->mm.lock);
if (obj->userptr.work == &work->work) {
struct sg_table *pages = ERR_PTR(ret);
@@ -542,13 +541,12 @@ __i915_gem_userptr_get_pages_worker(struct work_struct *_work)
obj->userptr.work = ERR_CAST(pages);
}
-
- i915_gem_object_put(obj);
- mutex_unlock(&dev->struct_mutex);
+ mutex_unlock(&obj->mm.lock);
release_pages(pvec, pinned, 0);
drm_free_large(pvec);
+ i915_gem_object_put_unlocked(obj);
put_task_struct(work->task);
kfree(work);
}
--
2.10.1
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