Re: [PATCH 2/2] Add drm buddy manager support to amdgpu driver

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Am 20.09.21 um 21:21 schrieb Arunpravin:
Replace drm_mm with drm buddy manager for
VRAM memory management

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@xxxxxxx>
---
  .../gpu/drm/amd/amdgpu/amdgpu_res_cursor.h    |  78 +++++--
  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h       |   3 +-
  drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c  | 216 ++++++++++--------
  3 files changed, 189 insertions(+), 108 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h
index acfa207cf970..ba24052e9062 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_res_cursor.h
@@ -30,12 +30,25 @@
  #include <drm/ttm/ttm_resource.h>
  #include <drm/ttm/ttm_range_manager.h>
+struct amdgpu_vram_mgr_node {
+	struct ttm_range_mgr_node tnode;

NAK, don't base this on ttm_range_mgr_node. Instead use ttm_resource.

And please name the member base instead.

+	struct list_head blocks;
+};
+
+static inline struct amdgpu_vram_mgr_node *
+to_amdgpu_vram_mgr_node(struct ttm_resource *res)
+{
+	return container_of(container_of(res, struct ttm_range_mgr_node, base),
+			struct amdgpu_vram_mgr_node, tnode);
+}
+

Maybe stuff that in a separate amdgpu_vram_mgr.h file together with all the other defines for the vram manager.

  /* state back for walking over vram_mgr and gtt_mgr allocations */
  struct amdgpu_res_cursor {
  	uint64_t		start;
  	uint64_t		size;
  	uint64_t		remaining;
-	struct drm_mm_node	*node;
+	void			*node;
+	uint32_t		mem_type;
  };
/**
@@ -52,8 +65,6 @@ static inline void amdgpu_res_first(struct ttm_resource *res,
  				    uint64_t start, uint64_t size,
  				    struct amdgpu_res_cursor *cur)
  {
-	struct drm_mm_node *node;
-
  	if (!res || res->mem_type == TTM_PL_SYSTEM) {
  		cur->start = start;
  		cur->size = size;
@@ -65,14 +76,39 @@ static inline void amdgpu_res_first(struct ttm_resource *res,
BUG_ON(start + size > res->num_pages << PAGE_SHIFT); - node = to_ttm_range_mgr_node(res)->mm_nodes;
-	while (start >= node->size << PAGE_SHIFT)
-		start -= node++->size << PAGE_SHIFT;
+	cur->mem_type = res->mem_type;
+
+	if (cur->mem_type == TTM_PL_VRAM) {

Rather use a switch/case here.

+		struct drm_buddy_block *block;
+		struct list_head *head, *next;
+
+		head = &to_amdgpu_vram_mgr_node(res)->blocks;
+
+		block = list_first_entry_or_null(head, struct drm_buddy_block, link);
+		while (start >= block->size << PAGE_SHIFT) {
+			start -= block->size << PAGE_SHIFT;
+
+			next = block->link.next;
+			if (next != head)
+				block = list_entry(next, struct drm_buddy_block, link);
+		}
- cur->start = (node->start << PAGE_SHIFT) + start;
-	cur->size = min((node->size << PAGE_SHIFT) - start, size);
-	cur->remaining = size;
-	cur->node = node;
+		cur->start = (block->start << PAGE_SHIFT) + start;
+		cur->size = min((block->size << PAGE_SHIFT) - start, size);
+		cur->remaining = size;
+		cur->node = block;
+	} else if (cur->mem_type == TTM_PL_TT) {
+		struct drm_mm_node *node;
+
+		node = to_ttm_range_mgr_node(res)->mm_nodes;
+		while (start >= node->size << PAGE_SHIFT)
+			start -= node++->size << PAGE_SHIFT;
+
+		cur->start = (node->start << PAGE_SHIFT) + start;
+		cur->size = min((node->size << PAGE_SHIFT) - start, size);
+		cur->remaining = size;
+		cur->node = node;

With a default handling for other placement types.

+	}
  }
/**
@@ -85,8 +121,6 @@ static inline void amdgpu_res_first(struct ttm_resource *res,
   */
  static inline void amdgpu_res_next(struct amdgpu_res_cursor *cur, uint64_t size)
  {
-	struct drm_mm_node *node = cur->node;
-
  	BUG_ON(size > cur->remaining);
cur->remaining -= size;
@@ -99,9 +133,23 @@ static inline void amdgpu_res_next(struct amdgpu_res_cursor *cur, uint64_t size)
  		return;
  	}
- cur->node = ++node;
-	cur->start = node->start << PAGE_SHIFT;
-	cur->size = min(node->size << PAGE_SHIFT, cur->remaining);
+	if (cur->mem_type == TTM_PL_VRAM) {
+		struct drm_buddy_block *block = cur->node;
+		struct list_head *next;
+
+		next = block->link.next;
+		block = list_entry(next, struct drm_buddy_block, link);
+
+		cur->node = block;
+		cur->start = block->start << PAGE_SHIFT;
+		cur->size = min(block->size << PAGE_SHIFT, cur->remaining);
+	} else if (cur->mem_type == TTM_PL_TT) {
+		struct drm_mm_node *node = cur->node;
+
+		cur->node = ++node;
+		cur->start = node->start << PAGE_SHIFT;
+		cur->size = min(node->size << PAGE_SHIFT, cur->remaining);
+	}
  }
#endif
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
index e69f3e8e06e5..96c8e8aaa0ee 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
@@ -26,6 +26,7 @@
#include <linux/dma-direction.h>
  #include <drm/gpu_scheduler.h>
+#include <drm/drm_buddy.h>
  #include "amdgpu.h"
#define AMDGPU_PL_GDS (TTM_PL_PRIV + 0)
@@ -40,7 +41,7 @@
struct amdgpu_vram_mgr {
  	struct ttm_resource_manager manager;
-	struct drm_mm mm;
+	struct drm_buddy_mm mm;
  	spinlock_t lock;
  	struct list_head reservations_pending;
  	struct list_head reserved_pages;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 7b2b0980ec41..de0c5f4cabaf 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -23,7 +23,9 @@
   */
#include <linux/dma-mapping.h>
+#include <linux/list_sort.h>
  #include <drm/ttm/ttm_range_manager.h>
+#include <drm/drm_buddy.h>
#include "amdgpu.h"
  #include "amdgpu_vm.h"
@@ -33,7 +35,7 @@
struct amdgpu_vram_reservation {
  	struct list_head node;
-	struct drm_mm_node mm_node;
+	struct drm_buddy_block mm_node;
  };
static inline struct amdgpu_vram_mgr *
@@ -196,10 +198,10 @@ const struct attribute_group amdgpu_vram_mgr_attr_group = {
   * Calculate how many bytes of the MM node are inside visible VRAM
   */
  static u64 amdgpu_vram_mgr_vis_size(struct amdgpu_device *adev,
-				    struct drm_mm_node *node)
+				    struct drm_buddy_block *block)
  {
-	uint64_t start = node->start << PAGE_SHIFT;
-	uint64_t end = (node->size + node->start) << PAGE_SHIFT;
+	uint64_t start = block->start << PAGE_SHIFT;
+	uint64_t end = (block->size + block->start) << PAGE_SHIFT;
if (start >= adev->gmc.visible_vram_size)
  		return 0;
@@ -220,8 +222,8 @@ u64 amdgpu_vram_mgr_bo_visible_size(struct amdgpu_bo *bo)
  {
  	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
  	struct ttm_resource *res = bo->tbo.resource;
-	unsigned pages = res->num_pages;
-	struct drm_mm_node *mm;
+	struct amdgpu_vram_mgr_node *vnode = to_amdgpu_vram_mgr_node(res);
+	struct drm_buddy_block *block;
  	u64 usage;
if (amdgpu_gmc_vram_full_visible(&adev->gmc))
@@ -230,9 +232,8 @@ u64 amdgpu_vram_mgr_bo_visible_size(struct amdgpu_bo *bo)
  	if (res->start >= adev->gmc.visible_vram_size >> PAGE_SHIFT)
  		return 0;
- mm = &container_of(res, struct ttm_range_mgr_node, base)->mm_nodes[0];
-	for (usage = 0; pages; pages -= mm->size, mm++)
-		usage += amdgpu_vram_mgr_vis_size(adev, mm);
+	list_for_each_entry(block, &vnode->blocks, link)
+		usage += amdgpu_vram_mgr_vis_size(adev, block);
return usage;
  }
@@ -242,12 +243,15 @@ static void amdgpu_vram_mgr_do_reserve(struct ttm_resource_manager *man)
  {
  	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
  	struct amdgpu_device *adev = to_amdgpu_device(mgr);
-	struct drm_mm *mm = &mgr->mm;
+	struct drm_buddy_mm *mm = &mgr->mm;
  	struct amdgpu_vram_reservation *rsv, *temp;
  	uint64_t vis_usage;
+	int r = 0;
list_for_each_entry_safe(rsv, temp, &mgr->reservations_pending, node) {
-		if (drm_mm_reserve_node(mm, &rsv->mm_node))
+		r = drm_buddy_alloc_range(mm, &rsv->node, rsv->mm_node.start, rsv->mm_node.size);
+
+		if (unlikely(r))
  			continue;
dev_dbg(adev->dev, "Reservation 0x%llx - %lld, Succeeded\n",
@@ -333,26 +337,16 @@ int amdgpu_vram_mgr_query_page_status(struct ttm_resource_manager *man,
  	return ret;
  }
-/**
- * amdgpu_vram_mgr_virt_start - update virtual start address
- *
- * @mem: ttm_resource to update
- * @node: just allocated node
- *
- * Calculate a virtual BO start address to easily check if everything is CPU
- * accessible.
- */
-static void amdgpu_vram_mgr_virt_start(struct ttm_resource *mem,
-				       struct drm_mm_node *node)
+static int sort_blocks(void *priv, const struct list_head *A,
+					const struct list_head *B)

Please prefix all function with amdgpu_vram_mgr_.

  {
-	unsigned long start;
+	struct drm_buddy_block *a = list_entry(A, typeof(*a), link);
+	struct drm_buddy_block *b = list_entry(B, typeof(*b), link);
- start = node->start + node->size;
-	if (start > mem->num_pages)
-		start -= mem->num_pages;
+	if (a->start < b->start)
+		return -1;
  	else
-		start = 0;
-	mem->start = max(mem->start, start);
+		return 1;
  }
/**
@@ -370,15 +364,20 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  			       const struct ttm_place *place,
  			       struct ttm_resource **res)
  {
-	unsigned long lpfn, num_nodes, pages_per_node, pages_left, pages;
+	unsigned long lpfn, pages_per_node, pages_left, pages;
  	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
  	struct amdgpu_device *adev = to_amdgpu_device(mgr);
  	uint64_t vis_usage = 0, mem_bytes, max_bytes;
+	struct amdgpu_vram_mgr_node *vnode;
+	struct drm_buddy_mm *mm = &mgr->mm;
  	struct ttm_range_mgr_node *node;
-	struct drm_mm *mm = &mgr->mm;
-	enum drm_mm_insert_mode mode;
+	enum drm_buddy_alloc_mode mode;
+	struct drm_buddy_block *block;
+	unsigned int visible_pfn;
+	bool bar_limit_enabled;
+	unsigned long n_pages;
  	unsigned i;
-	int r;
+	int r = 0;

Please don't initialize the return type here. That's considered bad coding style.

lpfn = place->lpfn;
  	if (!lpfn)
@@ -395,10 +394,9 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  		goto error_sub;
  	}
- if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
+	if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
  		pages_per_node = ~0ul;
-		num_nodes = 1;
-	} else {
+	else {
  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
  		pages_per_node = HPAGE_PMD_NR;
  #else
@@ -407,57 +405,97 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  #endif
  		pages_per_node = max_t(uint32_t, pages_per_node,
  				       tbo->page_alignment);
-		num_nodes = DIV_ROUND_UP_ULL(PFN_UP(mem_bytes), pages_per_node);
  	}
- node = kvmalloc(struct_size(node, mm_nodes, num_nodes),
-			GFP_KERNEL | __GFP_ZERO);
-	if (!node) {
+	vnode = kzalloc(sizeof(*vnode), GFP_KERNEL);
+
+	if (!vnode) {
  		r = -ENOMEM;
  		goto error_sub;
  	}
+ node = &vnode->tnode;
+
  	ttm_resource_init(tbo, place, &node->base);
- mode = DRM_MM_INSERT_BEST;
-	if (place->flags & TTM_PL_FLAG_TOPDOWN)
-		mode = DRM_MM_INSERT_HIGH;
+	bar_limit_enabled = !(amdgpu_gmc_vram_full_visible(&adev->gmc));
+
+	visible_pfn = adev->gmc.visible_vram_size >> PAGE_SHIFT;
+
+	mode = DRM_BUDDY_BOTTOM_UP;
+	if (!place->fpfn && lpfn == man->size &&
+					(place->flags & TTM_PL_FLAG_TOPDOWN))
+		/* Allocate blocks from CPU non-mappable (TOP-DOWN) region */
+		mode = DRM_BUDDY_TOP_DOWN;
+	else if (place->fpfn || (lpfn != man->size && lpfn != visible_pfn))
+		/* Allocate blocks in desired range */
+		mode = DRM_BUDDY_ALLOC_RANGE;
pages_left = node->base.num_pages; /* Limit maximum size to 2GB due to SG table limitations */
  	pages = min(pages_left, 2UL << (30 - PAGE_SHIFT));
+ INIT_LIST_HEAD(&vnode->blocks);
+
  	i = 0;
-	spin_lock(&mgr->lock);
-	while (pages_left) {
-		uint32_t alignment = tbo->page_alignment;
-
-		if (pages >= pages_per_node)
-			alignment = pages_per_node;
-
-		r = drm_mm_insert_node_in_range(mm, &node->mm_nodes[i], pages,
-						alignment, 0, place->fpfn,
-						lpfn, mode);
-		if (unlikely(r)) {
-			if (pages > pages_per_node) {
-				if (is_power_of_2(pages))
-					pages = pages / 2;
-				else
-					pages = rounddown_pow_of_two(pages);
-				continue;
-			}
-			goto error_free;
-		}
+	if (mode == DRM_BUDDY_ALLOC_RANGE) {
+		r = drm_buddy_alloc_range(mm, &vnode->blocks,
+				(uint64_t)place->fpfn << PAGE_SHIFT, pages << PAGE_SHIFT);

That handling won't work. It's possible that you need contiguous memory in a specific range.

+
+		if (unlikely(r))
+			goto error_free_res;
+	} else {
+		while (pages_left) {
+			if (pages >= pages_per_node)
+				pages = pages_per_node;
+
+			n_pages = pages;
+
+			if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
+				n_pages = roundup_pow_of_two(n_pages);

That approach won't work either. For contiguous allocation you need to allocate one big chunk and then free up what you don't need at the end.

+
+			do {
+				unsigned int order;
+
+				order = fls(n_pages) - 1;
+				BUG_ON(order > mm->max_order);
+
+				spin_lock(&mgr->lock);
+				block = drm_buddy_alloc(mm, order, bar_limit_enabled,
+									visible_pfn, mode);

That doesn't seem to make much sense either. The backend allocator should not care about the BAR size nor the visible_pfn.

+				spin_unlock(&mgr->lock);
- vis_usage += amdgpu_vram_mgr_vis_size(adev, &node->mm_nodes[i]);
-		amdgpu_vram_mgr_virt_start(&node->base, &node->mm_nodes[i]);
-		pages_left -= pages;
-		++i;
+				if (IS_ERR(block)) {
+					r = -ENOSPC;
+					goto error_free_blocks;
+				}
- if (pages > pages_left)
-			pages = pages_left;
+				n_pages -= BIT(order);
+
+				list_add_tail(&block->link, &vnode->blocks);
+
+				if (!n_pages)
+					break;
+			} while (1);
+
+			pages_left -= pages;
+			++i;
+
+			if (pages > pages_left)
+				pages = pages_left;
+		}
  	}
+
+	spin_lock(&mgr->lock);
+	list_sort(NULL, &vnode->blocks, sort_blocks);

Why do you sort the list here?

Regards,
Christian.

+
+	list_for_each_entry(block, &vnode->blocks, link)
+		vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
+
+	block = list_first_entry_or_null(&vnode->blocks,
+			struct drm_buddy_block, link);
+	node->base.start = block->start;
  	spin_unlock(&mgr->lock);
if (i == 1)
@@ -472,12 +510,12 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  	*res = &node->base;
  	return 0;
-error_free:
-	while (i--)
-		drm_mm_remove_node(&node->mm_nodes[i]);
+error_free_blocks:
+	spin_lock(&mgr->lock);
+	drm_buddy_free_list(mm, &vnode->blocks);
  	spin_unlock(&mgr->lock);
-	kvfree(node);
-
+error_free_res:
+	kfree(vnode);
  error_sub:
  	atomic64_sub(mem_bytes, &mgr->usage);
  	return r;
@@ -494,28 +532,28 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
  static void amdgpu_vram_mgr_del(struct ttm_resource_manager *man,
  				struct ttm_resource *res)
  {
-	struct ttm_range_mgr_node *node = to_ttm_range_mgr_node(res);
+	struct amdgpu_vram_mgr_node *vnode = to_amdgpu_vram_mgr_node(res);
  	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
  	struct amdgpu_device *adev = to_amdgpu_device(mgr);
+	struct drm_buddy_mm *mm = &mgr->mm;
+	struct drm_buddy_block *block;
  	uint64_t usage = 0, vis_usage = 0;
-	unsigned i, pages;
spin_lock(&mgr->lock);
-	for (i = 0, pages = res->num_pages; pages;
-	     pages -= node->mm_nodes[i].size, ++i) {
-		struct drm_mm_node *mm = &node->mm_nodes[i];
-
-		drm_mm_remove_node(mm);
-		usage += mm->size << PAGE_SHIFT;
-		vis_usage += amdgpu_vram_mgr_vis_size(adev, mm);
+	list_for_each_entry(block, &vnode->blocks, link) {
+		usage += block->size << PAGE_SHIFT;
+		vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
  	}
+
  	amdgpu_vram_mgr_do_reserve(man);
+
+	drm_buddy_free_list(mm, &vnode->blocks);
  	spin_unlock(&mgr->lock);
atomic64_sub(usage, &mgr->usage);
  	atomic64_sub(vis_usage, &mgr->vis_usage);
- kvfree(node);
+	kfree(vnode);
  }
/**
@@ -668,12 +706,6 @@ uint64_t amdgpu_vram_mgr_vis_usage(struct ttm_resource_manager *man)
  static void amdgpu_vram_mgr_debug(struct ttm_resource_manager *man,
  				  struct drm_printer *printer)
  {
-	struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);
-
-	spin_lock(&mgr->lock);
-	drm_mm_print(&mgr->mm, printer);
-	spin_unlock(&mgr->lock);
-
  	drm_printf(printer, "man size:%llu pages, ram usage:%lluMB, vis usage:%lluMB\n",
  		   man->size, amdgpu_vram_mgr_usage(man) >> 20,
  		   amdgpu_vram_mgr_vis_usage(man) >> 20);
@@ -701,7 +733,7 @@ int amdgpu_vram_mgr_init(struct amdgpu_device *adev)
man->func = &amdgpu_vram_mgr_func; - drm_mm_init(&mgr->mm, 0, man->size);
+	drm_buddy_init(&mgr->mm, man->size << PAGE_SHIFT, PAGE_SIZE);
  	spin_lock_init(&mgr->lock);
  	INIT_LIST_HEAD(&mgr->reservations_pending);
  	INIT_LIST_HEAD(&mgr->reserved_pages);
@@ -737,10 +769,10 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device *adev)
  		kfree(rsv);
list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, node) {
-		drm_mm_remove_node(&rsv->mm_node);
+		drm_buddy_free(&mgr->mm, &rsv->mm_node);
  		kfree(rsv);
  	}
-	drm_mm_takedown(&mgr->mm);
+	drm_buddy_fini(&mgr->mm);
  	spin_unlock(&mgr->lock);
ttm_resource_manager_cleanup(man);




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