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 | 20 +++++++++----------
drivers/gpu/drm/i915/i915_gem_batch_pool.c | 4 ++--
drivers/gpu/drm/i915/i915_gem_context.c | 2 +-
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 10 +++++-----
drivers/gpu/drm/i915/i915_gem_gtt.c | 2 +-
drivers/gpu/drm/i915/i915_gem_shrinker.c | 5 +++--
8 files changed, 53 insertions(+), 23 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index dee66807c6bd..6b14c59828e3 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -136,7 +136,7 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
seq_printf(m, "%pK: %s%s%s%s %8zdKiB %02x %02x [ ",
&obj->base,
- obj->active ? "*" : " ",
+ i915_gem_object_is_active(obj) ? "*" : " ",
get_pin_flag(obj),
get_tiling_flag(obj),
get_global_flag(obj),
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index efa43411f0eb..1ecff535973e 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2031,12 +2031,16 @@ 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_RINGS;
+#define I915_BO_ACTIVE_SHIFT 0
+#define I915_BO_ACTIVE_MASK ((1 << I915_NUM_RINGS) - 1)
+#define I915_BO_ACTIVE(bo) ((bo)->flags & (I915_BO_ACTIVE_MASK << I915_BO_ACTIVE_SHIFT))
+#define __I915_BO_ACTIVE(bo) (READ_ONCE((bo)->flags) & (I915_BO_ACTIVE_MASK << I915_BO_ACTIVE_SHIFT))
/**
* This is set if the object has been written to since last bound
@@ -2151,6 +2155,31 @@ struct drm_i915_gem_object {
#define GEM_BUG_ON(expr)
#endif
+static inline bool
+i915_gem_object_is_active(const struct drm_i915_gem_object *obj)
+{
+ return obj->flags & (I915_BO_ACTIVE_MASK << I915_BO_ACTIVE_SHIFT);
+}
+
+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));
+}
+
void i915_gem_track_fb(struct drm_i915_gem_object *old,
struct drm_i915_gem_object *new,
unsigned frontbuffer_bits);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 74c56716a304..6712ecf1239b 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1130,7 +1130,7 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
{
int ret, i;
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
return 0;
if (readonly) {
@@ -1143,7 +1143,7 @@ i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
if (ret)
return ret;
}
- GEM_BUG_ON(obj->active);
+ GEM_BUG_ON(i915_gem_object_is_active(obj));
}
return 0;
@@ -1165,7 +1165,7 @@ 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);
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
return 0;
if (readonly) {
@@ -2080,10 +2080,10 @@ 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[ring]);
- GEM_BUG_ON((obj->active & (1 << ring)) == 0);
+ GEM_BUG_ON(!i915_gem_object_has_active_engine(obj, ring));
- obj->active &= ~(1 << ring);
- if (obj->active)
+ i915_gem_object_unset_active(obj, ring);
+ if (i915_gem_object_is_active(obj))
return;
/* Bump our place on the bound list to keep it roughly in LRU order
@@ -2373,7 +2373,7 @@ i915_gem_object_flush_active(struct drm_i915_gem_object *obj)
{
int i;
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
return;
for (i = 0; i < I915_NUM_RINGS; i++) {
@@ -2459,7 +2459,7 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
/* Need to make sure the object gets inactive eventually. */
i915_gem_object_flush_active(obj);
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
goto out;
/* Do this after OLR check to make sure we make forward progress polling
@@ -2557,7 +2557,7 @@ i915_gem_object_sync(struct drm_i915_gem_object *obj,
struct drm_i915_gem_request *req[I915_NUM_RINGS];
int ret, i, n;
- if (!obj->active)
+ if (!i915_gem_object_is_active(obj))
return 0;
n = 0;
@@ -3593,7 +3593,7 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data,
i915_gem_object_flush_active(obj);
BUILD_BUG_ON(I915_NUM_RINGS > 16);
- args->busy = obj->active << 16;
+ args->busy = I915_BO_ACTIVE(obj) << 16;
if (obj->last_write.request)
args->busy |= obj->last_write.request->engine->id;
diff --git a/drivers/gpu/drm/i915/i915_gem_batch_pool.c b/drivers/gpu/drm/i915/i915_gem_batch_pool.c
index d4318665ac6c..5ec5b1439e1f 100644
--- a/drivers/gpu/drm/i915/i915_gem_batch_pool.c
+++ b/drivers/gpu/drm/i915/i915_gem_batch_pool.c
@@ -115,14 +115,14 @@ i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
list_for_each_entry_safe(tmp, next, list, batch_pool_link) {
/* The batches are strictly LRU ordered */
- if (tmp->active) {
+ if (i915_gem_object_is_active(tmp)) {
struct drm_i915_gem_request *rq;
rq = tmp->last_read[pool->engine->id].request;
if (!i915_gem_request_completed(rq))
break;
- GEM_BUG_ON(tmp->active & ~intel_engine_flag(pool->engine));
+ GEM_BUG_ON((tmp->flags >> I915_BO_ACTIVE_SHIFT) & (~intel_engine_flag(pool->engine) & I915_BO_ACTIVE_MASK));
GEM_BUG_ON(tmp->last_write.request);
}
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 15d5a5d247e0..9250a7405807 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -427,7 +427,7 @@ void i915_gem_context_fini(struct drm_device *dev)
WARN_ON(!dev_priv->ring[RCS].last_context);
if (dev_priv->ring[RCS].last_context == dctx) {
/* Fake switch to NULL context */
- WARN_ON(dctx->legacy_hw_ctx.rcs_state->active);
+ WARN_ON(i915_gem_object_is_active(dctx->legacy_hw_ctx.rcs_state));
i915_gem_object_ggtt_unpin(dctx->legacy_hw_ctx.rcs_state);
i915_gem_context_unreference(dctx);
dev_priv->ring[RCS].last_context = NULL;
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 79dbd74b73c2..e66864bdbfb4 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -515,7 +515,7 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
}
/* We can't wait for rendering with pagefaults disabled */
- if (obj->active && pagefault_disabled())
+ if (i915_gem_object_is_active(obj) && pagefault_disabled())
return -EFAULT;
if (use_cpu_reloc(obj))
@@ -977,7 +977,7 @@ 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 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;
@@ -986,7 +986,7 @@ 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;
@@ -1145,9 +1145,9 @@ 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))
drm_gem_object_reference(&obj->base);
- obj->active |= 1 << engine;
+ i915_gem_object_set_active(obj, engine);
i915_gem_request_mark_active(req, &obj->last_read[engine]);
if (flags & EXEC_OBJECT_WRITE) {
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 8f3b2f051918..6652df57e5b0 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -3229,7 +3229,7 @@ i915_vma_retire(struct i915_gem_active *active,
container_of(active, struct i915_vma, last_read[engine]);
GEM_BUG_ON((vma->active & (1 << engine)) == 0);
- GEM_BUG_ON((vma->obj->active & vma->active) != vma->active);
+ GEM_BUG_ON(((vma->obj->flags >> I915_BO_ACTIVE_SHIFT) & vma->active) != vma->active);
vma->active &= ~(1 << engine);
if (vma->active)
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index 67f3eb9a8391..4d44def8fb03 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -150,7 +150,8 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
obj->madv != I915_MADV_DONTNEED)
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))
@@ -233,7 +234,7 @@ 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;
}
--
2.7.0.rc3
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