We are motivated to avoid using a bitfield for obj->active for a couple
of reasons. Firstly, we wish to document our lockless read of obj->active
using READ_ONCE inside i915_gem_busy_ioctl() and that requires an
integral type (i.e. not a bitfield). Secondly, gcc produces abysmal code
when presented with a bitfield and that shows up high on the profiles of
request tracking (mainly due to excess memory traffic as it converts
the bitfield to a register and back and generates frequent AGI in the
process).
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_debugfs.c | 2 +-
drivers/gpu/drm/i915/i915_drv.h | 31 +++++++++++++++++++++++++++++-
drivers/gpu/drm/i915/i915_gem.c | 16 +++++++--------
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 10 +++++-----
drivers/gpu/drm/i915/i915_gem_shrinker.c | 5 +++--
drivers/gpu/drm/i915/i915_gem_userptr.c | 2 +-
6 files changed, 48 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 10a346237795..920a2de95cd5 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -91,7 +91,7 @@ static int i915_capabilities(struct seq_file *m, void *data)
static char get_active_flag(struct drm_i915_gem_object *obj)
{
- return obj->active ? '*' : ' ';
+ return i915_gem_object_is_active(obj) ? '*' : ' ';
}
static char get_pin_flag(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b6b9a1f78238..309000af003d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2155,12 +2155,16 @@ struct drm_i915_gem_object {
struct list_head batch_pool_link;
+ unsigned long flags;
/**
* This is set if the object is on the active lists (has pending
* rendering and so a non-zero seqno), and is not set if it i s on
* inactive (ready to be unbound) list.
*/
- unsigned int active:I915_NUM_ENGINES;
+#define I915_BO_ACTIVE_SHIFT 0
+#define I915_BO_ACTIVE_MASK ((1 << I915_NUM_ENGINES) - 1)
+#define __I915_BO_ACTIVE(bo) \
+ ((READ_ONCE((bo)->flags) >> I915_BO_ACTIVE_SHIFT) & I915_BO_ACTIVE_MASK)
/**
* This is set if the object has been written to since last bound
@@ -2325,6 +2329,31 @@ i915_gem_object_has_struct_page(const struct drm_i915_gem_object *obj)
return obj->ops->flags & I915_GEM_OBJECT_HAS_STRUCT_PAGE;
}
+static inline unsigned long
+i915_gem_object_is_active(const struct drm_i915_gem_object *obj)
+{
+ return (obj->flags >> I915_BO_ACTIVE_SHIFT) & I915_BO_ACTIVE_MASK;
+}
+
+static inline void
+i915_gem_object_set_active(struct drm_i915_gem_object *obj, int engine)
+{
+ obj->flags |= 1 << (engine + I915_BO_ACTIVE_SHIFT);
+}
+
+static inline void
+i915_gem_object_unset_active(struct drm_i915_gem_object *obj, int engine)
+{
+ obj->flags &= ~(1 << (engine + I915_BO_ACTIVE_SHIFT));
+}
+
+static inline bool
+i915_gem_object_has_active_engine(const struct drm_i915_gem_object *obj,
+ int engine)
+{
+ return obj->flags & (1 << (engine + I915_BO_ACTIVE_SHIFT));
+}
+
/*
* Optimised SGL iterator for GEM objects
*/
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index bc5bc5ccdde0..ca9741525bf4 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1354,7 +1354,7 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
if (!readonly) {
active = obj->last_read;
- active_mask = obj->active;
+ active_mask = i915_gem_object_is_active(obj);
} else {
active_mask = 1;
active = &obj->last_write;
@@ -1398,7 +1398,7 @@ i915_gem_object_wait_rendering__nonblocking(struct drm_i915_gem_object *obj,
BUG_ON(!mutex_is_locked(&dev->struct_mutex));
BUG_ON(!dev_priv->mm.interruptible);
- active_mask = obj->active;
+ active_mask = i915_gem_object_is_active(obj);
if (!active_mask)
return 0;
@@ -2362,10 +2362,10 @@ i915_gem_object_retire__read(struct i915_gem_active *active,
struct drm_i915_gem_object *obj =
container_of(active, struct drm_i915_gem_object, last_read[idx]);
- GEM_BUG_ON((obj->active & (1 << idx)) == 0);
+ GEM_BUG_ON(!i915_gem_object_has_active_engine(obj, idx));
- obj->active &= ~(1 << idx);
- if (obj->active)
+ i915_gem_object_unset_active(obj, idx);
+ if (i915_gem_object_is_active(obj))
return;
/* Bump our place on the bound list to keep it roughly in LRU order
@@ -2669,7 +2669,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
return -ENOENT;
}
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
goto out;
for (i = 0; i < I915_NUM_ENGINES; i++) {
@@ -2757,7 +2757,7 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
lockdep_assert_held(&obj->base.dev->struct_mutex);
- active_mask = obj->active;
+ active_mask = i915_gem_object_is_active(obj);
if (!active_mask)
return 0;
@@ -3801,7 +3801,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
* become non-busy without any further actions.
*/
args->busy = 0;
- if (obj->active) {
+ if (i915_gem_object_is_active(obj)) {
struct drm_i915_gem_request *req;
int i;
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 0b5b0020916b..0d28703d991a 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -433,7 +433,7 @@ relocate_entry_clflush(struct drm_i915_gem_object *obj,
static bool object_is_idle(struct drm_i915_gem_object *obj)
{
- unsigned long active = obj->active;
+ unsigned long active = i915_gem_object_is_active(obj);
int idx;
for_each_active(active, idx) {
@@ -993,7 +993,7 @@ static int
i915_gem_execbuffer_move_to_gpu(struct drm_i915_gem_request *req,
struct list_head *vmas)
{
- const unsigned other_rings = ~intel_engine_flag(req->engine);
+ const unsigned int other_rings = (~intel_engine_flag(req->engine) & I915_BO_ACTIVE_MASK) << I915_BO_ACTIVE_SHIFT;
struct i915_vma *vma;
uint32_t flush_domains = 0;
bool flush_chipset = false;
@@ -1002,7 +1002,7 @@ i915_gem_execbuffer_move_to_gpu(struct drm_i915_gem_request *req,
list_for_each_entry(vma, vmas, exec_list) {
struct drm_i915_gem_object *obj = vma->obj;
- if (obj->active & other_rings) {
+ if (obj->flags & other_rings) {
ret = i915_gem_object_sync(obj, req);
if (ret)
return ret;
@@ -1164,9 +1164,9 @@ void i915_vma_move_to_active(struct i915_vma *vma,
* add the active reference first and queue for it to be dropped
* *last*.
*/
- if (obj->active == 0)
+ if (!i915_gem_object_is_active(obj))
i915_gem_object_get(obj);
- obj->active |= 1 << idx;
+ i915_gem_object_set_active(obj, idx);
i915_gem_active_set(&obj->last_read[idx], req);
if (flags & EXEC_OBJECT_WRITE) {
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 673999acc1f9..33f8dcb9b8c4 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -168,7 +168,8 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
!is_vmalloc_addr(obj->mapping))
continue;
- if ((flags & I915_SHRINK_ACTIVE) == 0 && obj->active)
+ if ((flags & I915_SHRINK_ACTIVE) == 0 &&
+ i915_gem_object_is_active(obj))
continue;
if (!can_release_pages(obj))
@@ -253,7 +254,7 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
count += obj->base.size >> PAGE_SHIFT;
list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list) {
- if (!obj->active && can_release_pages(obj))
+ if (!i915_gem_object_is_active(obj) && can_release_pages(obj))
count += obj->base.size >> PAGE_SHIFT;
}
diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index 651a84ba840c..53f64fcc89ef 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -67,7 +67,7 @@ static void wait_rendering(struct drm_i915_gem_object *obj)
struct drm_i915_gem_request *requests[I915_NUM_ENGINES];
int i, n;
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
return;
n = 0;
--
2.8.1
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