diff mbox series

buddy

Message ID 20190628102944.2855-1-chris@chris-wilson.co.uk (mailing list archive)
State New, archived
Headers show
Series buddy | expand

Commit Message

Chris Wilson June 28, 2019, 10:29 a.m. UTC
A puzzle for you...

---
 drivers/gpu/drm/i915/i915_buddy.c           |  17 +-
 drivers/gpu/drm/i915/selftests/i915_buddy.c | 230 +++++++++++++++++++-
 2 files changed, 234 insertions(+), 13 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/i915_buddy.c b/drivers/gpu/drm/i915/i915_buddy.c
index c0ac68d71d94..e5667540282a 100644
--- a/drivers/gpu/drm/i915/i915_buddy.c
+++ b/drivers/gpu/drm/i915/i915_buddy.c
@@ -16,7 +16,7 @@  static void mark_allocated(struct i915_buddy_block *block)
 	block->header &= ~I915_BUDDY_HEADER_STATE;
 	block->header |= I915_BUDDY_ALLOCATED;
 
-	list_del_init(&block->link);
+	list_del(&block->link);
 }
 
 static void mark_free(struct i915_buddy_mm *mm,
@@ -34,7 +34,7 @@  static void mark_split(struct i915_buddy_block *block)
 	block->header &= ~I915_BUDDY_HEADER_STATE;
 	block->header |= I915_BUDDY_SPLIT;
 
-	list_del_init(&block->link);
+	list_del(&block->link);
 }
 
 int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 min_size)
@@ -170,9 +170,6 @@  static int split_block(struct i915_buddy_mm *mm,
 
 	block->left->parent = block;
 
-	INIT_LIST_HEAD(&block->left->link);
-	INIT_LIST_HEAD(&block->left->tmp_link);
-
 	block->right = kmem_cache_zalloc(mm->blocks, GFP_KERNEL);
 	if (!block->right) {
 		kmem_cache_free(mm->blocks, block->left);
@@ -184,9 +181,6 @@  static int split_block(struct i915_buddy_mm *mm,
 
 	block->right->parent = block;
 
-	INIT_LIST_HEAD(&block->right->link);
-	INIT_LIST_HEAD(&block->right->tmp_link);
-
 	mark_free(mm, block->left);
 	mark_free(mm, block->right);
 
@@ -213,9 +207,9 @@  get_buddy(struct i915_buddy_block *block)
 static void __i915_buddy_free(struct i915_buddy_mm *mm,
 			      struct i915_buddy_block *block)
 {
-	list_del_init(&block->link); /* We have ownership now */
+	struct i915_buddy_block *parent;
 
-	while (block->parent) {
+	while ((parent = block->parent)) {
 		struct i915_buddy_block *buddy;
 
 		buddy = get_buddy(block);
@@ -228,7 +222,7 @@  static void __i915_buddy_free(struct i915_buddy_mm *mm,
 		kmem_cache_free(mm->blocks, block);
 		kmem_cache_free(mm->blocks, buddy);
 
-		block = block->parent;
+		block = parent;
 	}
 
 	mark_free(mm, block);
@@ -248,6 +242,7 @@  void i915_buddy_free_list(struct i915_buddy_mm *mm,
 
 	list_for_each_entry_safe(block, on, objects, link)
 		i915_buddy_free(mm, block);
+	INIT_LIST_HEAD(objects);
 }
 
 /*
diff --git a/drivers/gpu/drm/i915/selftests/i915_buddy.c b/drivers/gpu/drm/i915/selftests/i915_buddy.c
index 2159aa9f4867..943a9d08d2f5 100644
--- a/drivers/gpu/drm/i915/selftests/i915_buddy.c
+++ b/drivers/gpu/drm/i915/selftests/i915_buddy.c
@@ -295,7 +295,7 @@  static void igt_mm_config(u64 *size, u64 *min_size)
 	*size = s;
 }
 
-static int igt_buddy_alloc(void *arg)
+static int igt_buddy_alloc_smoke(void *arg)
 {
 	struct i915_buddy_mm mm;
 	int max_order;
@@ -385,6 +385,229 @@  static int igt_buddy_alloc(void *arg)
 	return err;
 }
 
+static int igt_buddy_alloc_pessimistic(void *arg)
+{
+	const unsigned int max_order = 16;
+	struct i915_buddy_block *block, *bn;
+	struct i915_buddy_mm mm;
+	unsigned int order;
+	LIST_HEAD(blocks);
+	int err;
+
+	/*
+	 * Create a pot-sized mm, then allocate one of each possible
+	 * order within. This should leave the mm with exactly one
+	 * page left.
+	 */
+
+	err = i915_buddy_init(&mm, PAGE_SIZE << max_order, PAGE_SIZE);
+	if (err) {
+		pr_err("buddy_init failed(%d)\n", err);
+		return err;
+	}
+	GEM_BUG_ON(mm.max_order != max_order);
+
+	for (order = 0; order < max_order; order++) {
+		block = i915_buddy_alloc(&mm, order);
+		if (IS_ERR(block)) {
+			pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
+				order);
+			err = PTR_ERR(block);
+			goto err;
+		}
+
+		list_add_tail(&block->link, &blocks);
+	}
+
+	/* And now the last remaining block available */
+	block = i915_buddy_alloc(&mm, 0);
+	if (IS_ERR(block)) {
+		pr_info("buddy_alloc hit -ENOMEM on final alloc\n");
+		err = PTR_ERR(block);
+		goto err;
+	}
+	list_add_tail(&block->link, &blocks);
+
+	/* Should be completely full! */
+	for (order = max_order; order--; ) {
+		block = i915_buddy_alloc(&mm, order);
+		if (!IS_ERR(block)) {
+			pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
+				order);
+			list_add_tail(&block->link, &blocks);
+			err = -EINVAL;
+			goto err;
+		}
+	}
+
+	block = list_last_entry(&blocks, typeof(*block), link);
+	list_del(&block->link);
+	i915_buddy_free(&mm, block);
+
+	/* As we free in increasing size, we make available larger blocks */
+	order = 1;
+	list_for_each_entry_safe(block, bn, &blocks, link) {
+		list_del(&block->link);
+		i915_buddy_free(&mm, block);
+
+		block = i915_buddy_alloc(&mm, order);
+		if (IS_ERR(block)) {
+			pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
+				order);
+			err = PTR_ERR(block);
+			goto err;
+		}
+		i915_buddy_free(&mm, block);
+		order++;
+	}
+
+	/* To confirm, now the whole mm should be available */
+	block = i915_buddy_alloc(&mm, max_order);
+	if (IS_ERR(block)) {
+		pr_info("buddy_alloc (realloc) hit -ENOMEM with order=%d\n",
+			max_order);
+		err = PTR_ERR(block);
+		goto err;
+	}
+	i915_buddy_free(&mm, block);
+
+err:
+	i915_buddy_free_list(&mm, &blocks);
+	i915_buddy_fini(&mm);
+	return err;
+}
+
+static int igt_buddy_alloc_optimistic(void *arg)
+{
+	const int max_order = 16;
+	struct i915_buddy_block *block;
+	struct i915_buddy_mm mm;
+	LIST_HEAD(blocks);
+	int order;
+	int err;
+
+	/*
+	 * Create a mm with one block of each order available, and
+	 * try to allocate them all.
+	 */
+
+	err = i915_buddy_init(&mm,
+			      PAGE_SIZE * ((1 << (max_order + 1)) - 1),
+			      PAGE_SIZE);
+	if (err) {
+		pr_err("buddy_init failed(%d)\n", err);
+		return err;
+	}
+	GEM_BUG_ON(mm.max_order != max_order);
+
+	for (order = 0; order <= max_order; order++) {
+		block = i915_buddy_alloc(&mm, order);
+		if (IS_ERR(block)) {
+			pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
+				order);
+			err = PTR_ERR(block);
+			goto err;
+		}
+
+		list_add_tail(&block->link, &blocks);
+	}
+
+	/* Should be completely full! */
+	block = i915_buddy_alloc(&mm, 0);
+	if (!IS_ERR(block)) {
+		pr_info("buddy_alloc unexpectedly succeeded, it should be full!");
+		list_add_tail(&block->link, &blocks);
+		err = -EINVAL;
+		goto err;
+	}
+
+err:
+	i915_buddy_free_list(&mm, &blocks);
+	i915_buddy_fini(&mm);
+	return err;
+}
+
+static int igt_buddy_alloc_pathological(void *arg)
+{
+	const int max_order = 16;
+	struct i915_buddy_block *block;
+	struct i915_buddy_mm mm;
+	LIST_HEAD(blocks);
+	LIST_HEAD(buddies);
+	int order, top;
+	int err;
+
+	/*
+	 * Create a pot-sized mm, then allocate one of each possible
+	 * order within. This should leave the mm with exactly one
+	 * page left. Free the largest block, then whittle down again.
+	 * Eventually we will have a fully 50% fragmented mm.
+	 */
+
+	err = i915_buddy_init(&mm, PAGE_SIZE << max_order, PAGE_SIZE);
+	if (err) {
+		pr_err("buddy_init failed(%d)\n", err);
+		return err;
+	}
+	GEM_BUG_ON(mm.max_order != max_order);
+
+	for (top = max_order; top; top--) {
+		/* Make room by freeing the largest allocated block */
+		block = list_first_entry_or_null(&blocks, typeof(*block), link);
+		if (block) {
+			list_del(&block->link);
+			i915_buddy_free(&mm, block);
+		}
+
+		for (order = top; order--; ) {
+			block = i915_buddy_alloc(&mm, order);
+			if (IS_ERR(block)) {
+				pr_info("buddy_alloc hit -ENOMEM with order=%d, top=%d\n",
+					order, top);
+				err = PTR_ERR(block);
+				goto err;
+			}
+			list_add_tail(&block->link, &blocks);
+		}
+
+		block = i915_buddy_alloc(&mm, top);
+		if (!IS_ERR(block)) {
+			pr_info("buddy_alloc unexpectedly succeeded at top-order %d/%d, it should be full!",
+				top, max_order);
+			list_add_tail(&block->link, &blocks);
+			err = -EINVAL;
+			goto err;
+		}
+	}
+
+	/* Split the final block */
+	block = i915_buddy_alloc(&mm, 0);
+	if (IS_ERR(block)) {
+		pr_info("buddy_alloc hit -ENOMEM with order=%d\n",
+				0);
+		err = PTR_ERR(block);
+		goto err;
+	}
+	list_add_tail(&block->link, &blocks);
+
+	/* Nothing larger than blocks of min_size now available */
+	for (order = 1; order <= max_order; order++) {
+		block = i915_buddy_alloc(&mm, order);
+		if (!IS_ERR(block)) {
+			pr_info("buddy_alloc unexpectedly succeeded at order %d, it should be full!",
+				order);
+			list_add_tail(&block->link, &blocks);
+			err = -EINVAL;
+			goto err;
+		}
+	}
+
+err:
+	i915_buddy_free_list(&mm, &blocks);
+	i915_buddy_fini(&mm);
+	return err;
+}
+
 static int igt_buddy_alloc_range(void *arg)
 {
 	struct i915_buddy_mm mm;
@@ -483,7 +706,10 @@  static int igt_buddy_alloc_range(void *arg)
 int i915_buddy_mock_selftests(void)
 {
 	static const struct i915_subtest tests[] = {
-		SUBTEST(igt_buddy_alloc),
+		SUBTEST(igt_buddy_alloc_pessimistic),
+		SUBTEST(igt_buddy_alloc_optimistic),
+		SUBTEST(igt_buddy_alloc_pathological),
+		SUBTEST(igt_buddy_alloc_smoke),
 		SUBTEST(igt_buddy_alloc_range),
 	};