[Intel-gfx] [PATCH 112/190] drm/i915: Move obj->active:5 to obj->flags

Chris Wilson chris at chris-wilson.co.uk
Mon Jan 11 02:44:56 PST 2016


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 at chris-wilson.co.uk>
---
 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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