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

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

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