Re: [PATCH v11] drm/amdgpu: add drm buddy support to amdgpu

Am 23.03.22 um 07:25 schrieb Arunpravin Paneer Selvam:

[SNIP] @@ -415,48 +409,86 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man, goto error_fini; }

• mode = DRM_MM_INSERT_BEST;

• INIT_LIST_HEAD(&node->blocks);
• if (place->flags & TTM_PL_FLAG_TOPDOWN)

• mode = DRM_MM_INSERT_HIGH;
  

• node->flags |= DRM_BUDDY_TOPDOWN_ALLOCATION;
  
  

• pages_left = node->base.num_pages;

• if (place->fpfn || lpfn != man->size >> PAGE_SHIFT)

• /* Allocate blocks in desired range */
  

• node->flags |= DRM_BUDDY_RANGE_ALLOCATION;
  
  

• /* Limit maximum size to 2GB due to SG table limitations */
• pages = min(pages_left, 2UL << (30 - PAGE_SHIFT));

• BUG_ON(!node->base.num_pages);

Please drop this BUG_ON(). This is not something which prevents further data corruption, so the BUG_ON() is not justified.

• pages_left = node->base.num_pages;

  i = 0;

• spin_lock(&mgr->lock); while (pages_left) {

• uint32_t alignment = tbo->page_alignment;
  

• if (tbo->page_alignment)
  

• 	min_page_size = tbo->page_alignment << PAGE_SHIFT;
  

• else
  

• 	min_page_size = mgr->default_page_size;
  

The handling here looks extremely awkward to me.

min_page_size should be determined outside of the loop, based on default_page_size, alignment and contiguous flag.

Then why do you drop the lock and grab it again inside the loop? And what is "i" actually good for?

• /* Limit maximum size to 2GB due to SG table limitations */
  

• pages = min(pages_left, 2UL << (30 - PAGE_SHIFT));
  
  

  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;
  

• 	min_page_size = pages_per_node << PAGE_SHIFT;
  

• if (!is_contiguous && !IS_ALIGNED(pages, min_page_size >> PAGE_SHIFT))
  

• 	is_contiguous = 1;
  

• if (is_contiguous) {
  

• 	pages = roundup_pow_of_two(pages);
  

• 	min_page_size = pages << PAGE_SHIFT;
  

• 	if (pages > lpfn)
  

• 		lpfn = pages;
  

  }

• 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;
  

• BUG_ON(min_page_size < mm->chunk_size);
  

• mutex_lock(&mgr->lock);
  

• r = drm_buddy_alloc_blocks(mm, (u64)place->fpfn << PAGE_SHIFT,
  

• 			   (u64)lpfn << PAGE_SHIFT,
  

• 			   (u64)pages << PAGE_SHIFT,
  

• 			   min_page_size,
  

• 			   &node->blocks,
  

• 			   node->flags);
  

• mutex_unlock(&mgr->lock);
  

• if (unlikely(r))
  

• 	goto error_free_blocks;
  

• ++i;

  if (pages > pages_left)

• 	pages = pages_left;
  

• 	pages_left = 0;
  

• else
  

• 	pages_left -= pages;
  

  }

• spin_unlock(&mgr->lock);

• if (i == 1)

• /* Free unused pages for contiguous allocation */
• if (is_contiguous) {

Well that looks really odd, why is trimming not part of drm_buddy_alloc_blocks() ?

• u64 actual_size = (u64)node->base.num_pages << PAGE_SHIFT;
  

• mutex_lock(&mgr->lock);
  

• drm_buddy_block_trim(mm,
  

• 		     actual_size,
  

• 		     &node->blocks);
  

Why is the drm_buddy_block_trim() function given all the blocks and not just the last one?

Regards, Christian.

• mutex_unlock(&mgr->lock);
  

• }

• list_for_each_entry(block, &node->blocks, link)

• vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
  

• block = amdgpu_vram_mgr_first_block(&node->blocks);

• if (!block) {

• r = -EINVAL;
  

• goto error_fini;
  

• }

• node->base.start = amdgpu_node_start(block) >> PAGE_SHIFT;

• if (i == 1 && is_contiguous) node->base.placement |= TTM_PL_FLAG_CONTIGUOUS;

  if (adev->gmc.xgmi.connected_to_cpu)

@@ -468,13 +500,13 @@ 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]);
  

• spin_unlock(&mgr->lock);

+error_free_blocks:

• mutex_lock(&mgr->lock);
• drm_buddy_free_list(mm, &node->blocks);
• mutex_unlock(&mgr->lock); error_fini: ttm_resource_fini(man, &node->base);

• kvfree(node);

• kfree(node);

  return r; }

@@ -490,27 +522,26 @@ 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 *node = 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 = &mgr->mm;
• struct drm_buddy_block *block; uint64_t 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];
  

• mutex_lock(&mgr->lock);
• list_for_each_entry(block, &node->blocks, link)

• vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
  
  

• drm_mm_remove_node(mm);
  

• vis_usage += amdgpu_vram_mgr_vis_size(adev, mm);
  

• } amdgpu_vram_mgr_do_reserve(man);
• spin_unlock(&mgr->lock);

• drm_buddy_free_list(mm, &node->blocks);

• mutex_unlock(&mgr->lock);

  atomic64_sub(vis_usage, &mgr->vis_usage);

  ttm_resource_fini(man, res);

• kvfree(node);

• kfree(node); }

  /**

@@ -648,13 +679,22 @@ static void amdgpu_vram_mgr_debug(struct ttm_resource_manager *man, struct drm_printer *printer) { struct amdgpu_vram_mgr *mgr = to_vram_mgr(man);

• struct drm_buddy *mm = &mgr->mm;

• struct drm_buddy_block *block;

  drm_printf(printer, " vis usage:%llu\n", amdgpu_vram_mgr_vis_usage(mgr));

• spin_lock(&mgr->lock);
• drm_mm_print(&mgr->mm, printer);
• spin_unlock(&mgr->lock);

• mutex_lock(&mgr->lock);

• drm_printf(printer, "default_page_size: %lluKiB\n",

•    mgr->default_page_size >> 10);
  

• drm_buddy_print(mm, printer);

• drm_printf(printer, "reserved:\n");

• list_for_each_entry(block, &mgr->reserved_pages, link)

• drm_buddy_block_print(mm, block, printer);
  

• mutex_unlock(&mgr->lock); }

  static const struct ttm_resource_manager_func amdgpu_vram_mgr_func = {

@@ -674,16 +714,21 @@ int amdgpu_vram_mgr_init(struct amdgpu_device *adev) { struct amdgpu_vram_mgr *mgr = &adev->mman.vram_mgr; struct ttm_resource_manager *man = &mgr->manager;

• int err;

  ttm_resource_manager_init(man, &adev->mman.bdev, adev->gmc.real_vram_size);

  man->func = &amdgpu_vram_mgr_func;

• drm_mm_init(&mgr->mm, 0, man->size >> PAGE_SHIFT);
• spin_lock_init(&mgr->lock);

• err = drm_buddy_init(&mgr->mm, man->size, PAGE_SIZE);

• if (err)

• return err;
  

• mutex_init(&mgr->lock); INIT_LIST_HEAD(&mgr->reservations_pending); INIT_LIST_HEAD(&mgr->reserved_pages);

• mgr->default_page_size = PAGE_SIZE;

  ttm_set_driver_manager(&adev->mman.bdev, TTM_PL_VRAM, &mgr->manager); ttm_resource_manager_set_used(man, true);

@@ -711,16 +756,16 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device *adev) if (ret) return;

• spin_lock(&mgr->lock);

• mutex_lock(&mgr->lock); list_for_each_entry_safe(rsv, temp, &mgr->reservations_pending, node) kfree(rsv);

  list_for_each_entry_safe(rsv, temp, &mgr->reserved_pages, node) {

• drm_mm_remove_node(&rsv->mm_node);
  

• drm_buddy_free_list(&mgr->mm, &rsv->block);
  

  kfree(rsv); }

• drm_mm_takedown(&mgr->mm);
• spin_unlock(&mgr->lock);

• drm_buddy_fini(&mgr->mm);

• mutex_unlock(&mgr->lock);

  ttm_resource_manager_cleanup(man); ttm_set_driver_manager(&adev->mman.bdev, TTM_PL_VRAM, NULL);

base-commit: a678f97326454b60ffbbde6abf52d23997d71a27