[PATCH 14/70] drm/i915: Split batch pool into size buckets

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Now with the trimmed memcpy before the command parser, we try to
allocate many different sizes of batches, predominantly one or two
pages. We can therefore speed up searching for a good sized batch by
keeping the objects of buckets of roughly the same size.

v2: Add a comment about bucket sizes

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx
---
 drivers/gpu/drm/i915/i915_debugfs.c        | 46 ++++++++++++++++++----------
 drivers/gpu/drm/i915/i915_drv.h            |  2 +-
 drivers/gpu/drm/i915/i915_gem.c            |  2 +-
 drivers/gpu/drm/i915/i915_gem_batch_pool.c | 49 +++++++++++++++++++-----------
 drivers/gpu/drm/i915/i915_gem_batch_pool.h |  2 +-
 5 files changed, 64 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index f610a2cd2088..11eebc28775a 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -378,15 +378,17 @@ static void print_batch_pool_stats(struct seq_file *m,
 	struct drm_i915_gem_object *obj;
 	struct file_stats stats;
 	struct intel_engine_cs *ring;
-	int i;
+	int i, j;
 
 	memset(&stats, 0, sizeof(stats));
 
 	for_each_ring(ring, dev_priv, i) {
-		list_for_each_entry(obj,
-				    &ring->batch_pool.cache_list,
-				    batch_pool_list)
-			per_file_stats(0, obj, &stats);
+		for (j = 0; j < ARRAY_SIZE(ring->batch_pool.cache_list); j++) {
+			list_for_each_entry(obj,
+					    &ring->batch_pool.cache_list[j],
+					    batch_pool_link)
+				per_file_stats(0, obj, &stats);
+		}
 	}
 
 	print_file_stats(m, "batch pool", stats);
@@ -618,26 +620,38 @@ static int i915_gem_batch_pool_info(struct seq_file *m, void *data)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_object *obj;
 	struct intel_engine_cs *ring;
-	int count = 0;
-	int ret, i;
+	int total = 0;
+	int ret, i, j;
 
 	ret = mutex_lock_interruptible(&dev->struct_mutex);
 	if (ret)
 		return ret;
 
 	for_each_ring(ring, dev_priv, i) {
-		seq_printf(m, "%s cache:\n", ring->name);
-		list_for_each_entry(obj,
-				    &ring->batch_pool.cache_list,
-				    batch_pool_list) {
-			seq_puts(m, "   ");
-			describe_obj(m, obj);
-			seq_putc(m, '\n');
-			count++;
+		for (j = 0; j < ARRAY_SIZE(ring->batch_pool.cache_list); j++) {
+			int count;
+
+			count = 0;
+			list_for_each_entry(obj,
+					    &ring->batch_pool.cache_list[j],
+					    batch_pool_link)
+				count++;
+			seq_printf(m, "%s cache[%d]: %d objects\n",
+				   ring->name, j, count);
+
+			list_for_each_entry(obj,
+					    &ring->batch_pool.cache_list[j],
+					    batch_pool_link) {
+				seq_puts(m, "   ");
+				describe_obj(m, obj);
+				seq_putc(m, '\n');
+			}
+
+			total += count;
 		}
 	}
 
-	seq_printf(m, "total: %d\n", count);
+	seq_printf(m, "total: %d\n", total);
 
 	mutex_unlock(&dev->struct_mutex);
 
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 178da6eb4edb..cc7956c7f251 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1911,7 +1911,7 @@ struct drm_i915_gem_object {
 	/** Used in execbuf to temporarily hold a ref */
 	struct list_head obj_exec_link;
 
-	struct list_head batch_pool_list;
+	struct list_head batch_pool_link;
 
 	/**
 	 * This is set if the object is on the active lists (has pending
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 2282f579e101..c7d9ee2f708a 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4450,7 +4450,7 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj,
 	INIT_LIST_HEAD(&obj->ring_list);
 	INIT_LIST_HEAD(&obj->obj_exec_link);
 	INIT_LIST_HEAD(&obj->vma_list);
-	INIT_LIST_HEAD(&obj->batch_pool_list);
+	INIT_LIST_HEAD(&obj->batch_pool_link);
 
 	obj->ops = ops;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_batch_pool.c b/drivers/gpu/drm/i915/i915_gem_batch_pool.c
index 1287abf55b84..7bf2f3f2968e 100644
--- a/drivers/gpu/drm/i915/i915_gem_batch_pool.c
+++ b/drivers/gpu/drm/i915/i915_gem_batch_pool.c
@@ -47,8 +47,12 @@
 void i915_gem_batch_pool_init(struct drm_device *dev,
 			      struct i915_gem_batch_pool *pool)
 {
+	int n;
+
 	pool->dev = dev;
-	INIT_LIST_HEAD(&pool->cache_list);
+
+	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
+		INIT_LIST_HEAD(&pool->cache_list[n]);
 }
 
 /**
@@ -59,16 +63,20 @@ void i915_gem_batch_pool_init(struct drm_device *dev,
  */
 void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)
 {
+	int n;
+
 	WARN_ON(!mutex_is_locked(&pool->dev->struct_mutex));
 
-	while (!list_empty(&pool->cache_list)) {
-		struct drm_i915_gem_object *obj =
-			list_first_entry(&pool->cache_list,
-					 struct drm_i915_gem_object,
-					 batch_pool_list);
+	for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {
+		while (!list_empty(&pool->cache_list[n])) {
+			struct drm_i915_gem_object *obj =
+				list_first_entry(&pool->cache_list[n],
+						 struct drm_i915_gem_object,
+						 batch_pool_link);
 
-		list_del(&obj->batch_pool_list);
-		drm_gem_object_unreference(&obj->base);
+			list_del(&obj->batch_pool_link);
+			drm_gem_object_unreference(&obj->base);
+		}
 	}
 }
 
@@ -91,28 +99,33 @@ i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
 {
 	struct drm_i915_gem_object *obj = NULL;
 	struct drm_i915_gem_object *tmp, *next;
+	struct list_head *list;
+	int n;
 
 	WARN_ON(!mutex_is_locked(&pool->dev->struct_mutex));
 
-	list_for_each_entry_safe(tmp, next,
-				 &pool->cache_list, batch_pool_list) {
+	/* Compute a power-of-two bucket, but throw everything greater than
+	 * 16KiB into the same bucket: i.e. the the buckets hold objects of
+	 * (1 page, 2 pages, 4 pages, 8+ pages).
+	 */
+	n = fls(size >> PAGE_SHIFT) - 1;
+	if (n >= ARRAY_SIZE(pool->cache_list))
+		n = ARRAY_SIZE(pool->cache_list) - 1;
+	list = &pool->cache_list[n];
+
+	list_for_each_entry_safe(tmp, next, list, batch_pool_link) {
 		/* The batches are strictly LRU ordered */
 		if (tmp->active)
 			break;
 
 		/* While we're looping, do some clean up */
 		if (tmp->madv == __I915_MADV_PURGED) {
-			list_del(&tmp->batch_pool_list);
+			list_del(&tmp->batch_pool_link);
 			drm_gem_object_unreference(&tmp->base);
 			continue;
 		}
 
-		/*
-		 * Select a buffer that is at least as big as needed
-		 * but not 'too much' bigger. A better way to do this
-		 * might be to bucket the pool objects based on size.
-		 */
-		if (tmp->base.size >= size && tmp->base.size <= 2 * size) {
+		if (tmp->base.size >= size) {
 			obj = tmp;
 			break;
 		}
@@ -132,7 +145,7 @@ i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
 		obj->madv = I915_MADV_DONTNEED;
 	}
 
-	list_move_tail(&obj->batch_pool_list, &pool->cache_list);
+	list_move_tail(&obj->batch_pool_link, list);
 	i915_gem_object_pin_pages(obj);
 	return obj;
 }
diff --git a/drivers/gpu/drm/i915/i915_gem_batch_pool.h b/drivers/gpu/drm/i915/i915_gem_batch_pool.h
index 5ed70ef6a887..848e90703eed 100644
--- a/drivers/gpu/drm/i915/i915_gem_batch_pool.h
+++ b/drivers/gpu/drm/i915/i915_gem_batch_pool.h
@@ -29,7 +29,7 @@
 
 struct i915_gem_batch_pool {
 	struct drm_device *dev;
-	struct list_head cache_list;
+	struct list_head cache_list[4];
 };
 
 /* i915_gem_batch_pool.c */
-- 
2.1.4

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