On contiguous allocation, we round up the size
to the *next* power of 2, implement a function
to free the unused pages after the newly allocate block.
v2(Matthew Auld):
- replace function name 'drm_buddy_free_unused_pages' with
drm_buddy_block_trim
- replace input argument name 'actual_size' with 'new_size'
- add more validation checks for input arguments
- add overlaps check to avoid needless searching and splitting
- merged the below patch to see the feature in action
- add free unused pages support to i915 driver
- lock drm_buddy_block_trim() function as it calls mark_free/mark_split
are all globally visible
Signed-off-by: Arunpravin <arunpravin.paneersel...@amd.com>
---
drivers/gpu/drm/drm_buddy.c | 108 ++++++++++++++++++
drivers/gpu/drm/i915/i915_ttm_buddy_manager.c | 10 ++
include/drm/drm_buddy.h | 4 +
3 files changed, 122 insertions(+)
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 0a9db2981188..943fe2ad27bf 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -284,6 +284,114 @@ static inline bool contains(u64 s1, u64 e1, u64 s2, u64
e2)
return s1 <= s2 && e1 >= e2;
}
+/**
+ * drm_buddy_block_trim - free unused pages
+ *
+ * @mm: DRM buddy manager
+ * @new_size: original size requested
+ * @blocks: output list head to add allocated blocks
+ *
+ * For contiguous allocation, we round up the size to the nearest
+ * power of two value, drivers consume *actual* size, so remaining
+ * portions are unused and it can be freed.
+ *
+ * Returns:
+ * 0 on success, error code on failure.
+ */
+int drm_buddy_block_trim(struct drm_buddy_mm *mm,
+ u64 new_size,
+ struct list_head *blocks)
+{
+ struct drm_buddy_block *block;
+ struct drm_buddy_block *buddy;
+ u64 new_start;
+ u64 new_end;
+ LIST_HEAD(dfs);
+ u64 count = 0;
+ int err;
+
+ if (!list_is_singular(blocks))
+ return -EINVAL;
+
+ block = list_first_entry(blocks,
+ struct drm_buddy_block,
+ link);
+
+ if (!drm_buddy_block_is_allocated(block))
+ return -EINVAL;
+
+ if (new_size > drm_buddy_block_size(mm, block))
+ return -EINVAL;
+
+ if (!new_size && !IS_ALIGNED(new_size, mm->chunk_size))
+ return -EINVAL;
+
+ if (new_size == drm_buddy_block_size(mm, block))
+ return 0;
+
+ list_del(&block->link);
+
+ new_start = drm_buddy_block_offset(block);
+ new_end = new_start + new_size - 1;
+
+ mark_free(mm, block);
+
+ list_add(&block->tmp_link, &dfs);
+
+ do {
+ u64 block_start;
+ u64 block_end;
+
+ block = list_first_entry_or_null(&dfs,
+ struct drm_buddy_block,
+ tmp_link);
+ if (!block)
+ break;
+
+ list_del(&block->tmp_link);
+
+ if (count == new_size)
+ return 0;
+
+ block_start = drm_buddy_block_offset(block);
+ block_end = block_start + drm_buddy_block_size(mm, block) - 1;
+
+ if (!overlaps(new_start, new_end, block_start, block_end))
+ continue;
+
+ if (contains(new_start, new_end, block_start, block_end)) {
+ BUG_ON(!drm_buddy_block_is_free(block));
+
+ /* Allocate only required blocks */
+ mark_allocated(block);
+ mm->avail -= drm_buddy_block_size(mm, block);
+ list_add_tail(&block->link, blocks);
+ count += drm_buddy_block_size(mm, block);
+ continue;
+ }
+
+ if (!drm_buddy_block_is_split(block)) {
+ err = split_block(mm, block);
+ if (unlikely(err))
+ goto err_undo;
+ }
+
+ list_add(&block->right->tmp_link, &dfs);
+ list_add(&block->left->tmp_link, &dfs);
+ } while (1);
+
+ return -ENOSPC;
+
+err_undo:
+ buddy = get_buddy(block);
+ if (buddy &&
+ (drm_buddy_block_is_free(block) &&
+ drm_buddy_block_is_free(buddy)))
+ __drm_buddy_free(mm, block);
+ return err;
+}
+EXPORT_SYMBOL(drm_buddy_block_trim);
+
static struct drm_buddy_block *
alloc_range(struct drm_buddy_mm *mm,
u64 start, u64 end,
diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
index b6ed5b37cf18..5e1f8c443058 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -97,6 +97,16 @@ static int i915_ttm_buddy_man_alloc(struct
ttm_resource_manager *man,
if (unlikely(err))
goto err_free_blocks;
+ if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
+ mutex_lock(&bman->lock);
+ err = drm_buddy_block_trim(mm,
+ (u64)n_pages << PAGE_SHIFT,
+ &bman_res->blocks);
+ mutex_unlock(&bman->lock);
+ if (unlikely(err))
+ goto err_free_blocks;
+ }
+
*res = &bman_res->base;
return 0;
diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h
index cbe5e648440a..36e8f548acf7 100644
--- a/include/drm/drm_buddy.h
+++ b/include/drm/drm_buddy.h
@@ -145,6 +145,10 @@ int drm_buddy_alloc(struct drm_buddy_mm *mm,
struct list_head *blocks,
unsigned long flags);
+int drm_buddy_block_trim(struct drm_buddy_mm *mm,
+ u64 new_size,
+ struct list_head *blocks);
+
void drm_buddy_free(struct drm_buddy_mm *mm, struct drm_buddy_block *block);
void drm_buddy_free_list(struct drm_buddy_mm *mm, struct list_head *objects);
--
2.25.1
